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Original Contribution |

Aspirin Use and Risk of Colorectal Cancer According to BRAF Mutation Status FREE

Reiko Nishihara, PhD; Paul Lochhead, MB, ChB; Aya Kuchiba, PhD; Seungyoun Jung, ScD; Mai Yamauchi, PhD; Xiaoyun Liao, MD, PhD; Yu Imamura, MD, PhD; Zhi Rong Qian, MD, PhD; Teppei Morikawa, MD, PhD; Molin Wang, PhD; Donna Spiegelman, ScD; Eunyoung Cho, ScD; Edward Giovannucci, MD, ScD; Charles S. Fuchs, MD, MPH; Andrew T. Chan, MD, MPH; Shuji Ogino, MD, PhD, MS
[+] Author Affiliations

Author Affiliations: Department of Medical Oncology, Dana-Farber Cancer Institute (Drs Nishihara, Lochhead, Kuchiba, Yamauchi, Liao, Imamura, Qian, Morikawa, Fuchs, and Ogino), Channing Division of Network Medicine, Department of Medicine (Drs Jung, Wang, Spiegelman, Cho, Giovannucci, Fuchs, and Chan) and Department of Pathology (Dr Ogino), Brigham and Women's Hospital and Harvard Medical School, and Departments of Nutrition (Drs Nishihara, Kuchiba, and Giovannucci), Epidemiology (Drs Wang, Spiegelman, Giovannucci, and Ogino), and Biostatistics (Drs Wang and Spiegelman), Harvard School of Public Health, Boston, Massachusetts; Gastrointestinal Research Group, Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland (Dr Lochhead); Department of Pathology, University of Tokyo Hospital, Tokyo, Japan (Dr Morikawa); and Division of Gastroenterology, Massachusetts General Hospital, Boston (Dr Chan).


JAMA. 2013;309(24):2563-2571. doi:10.1001/jama.2013.6599.
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Importance Aspirin use reduces the risk of colorectal carcinoma. Experimental evidence implicates a role of RAF kinases in up-regulation of prostaglandin-endoperoxide synthase 2 (PTGS2, cyclooxygenase 2), suggesting that BRAF-mutant colonic cells might be less sensitive to the antitumor effects of aspirin than BRAF–wild-type neoplastic cells.

Objective To examine whether the association of aspirin intake with colorectal cancer risk differs according to status of tumor BRAF oncogene mutation.

Design and Setting We collected biennial questionnaire data on aspirin use and followed up participants in the Nurses' Health Study (from 1980) and the Health Professionals Follow-up Study (from 1986) until July 1, 2006, for cancer incidence and until January 1, 2012, for cancer mortality. Duplication-method Cox proportional cause-specific hazards regression for competing risks data was used to compute hazard ratios (HRs) for colorectal carcinoma incidence according to BRAF mutation status.

Main Outcomes and Measures Incidence of colorectal cancer cases according to tumor BRAF mutation status.

Results Among 127 865 individuals, with 3 165 985 person-years of follow-up, we identified 1226 incident rectal and colon cancers with available molecular data. Compared with nonuse, regular aspirin use was associated with lower BRAF–wild-type cancer risk (multivariable HR, 0.73; 95% CI, 0.64 to 0.83; age-adjusted incidence rate difference [RD], −9.7; 95% CI, −12.6 to −6.7 per 100 000 person-years). This association was observed irrespective of status of tumor PTGS2 expression or PIK3CA or KRAS mutation. In contrast, regular aspirin use was not associated with a lower risk of BRAF-mutated cancer (multivariable HR, 1.03; 95% CI, 0.76 to 1.38; age-adjusted, incidence RD, 0.7; 95% CI, −0.3 to 1.7 per 100 000 person-years: P for heterogeneity = .037, between BRAF–wild-type vs BRAF-mutated cancer risks). Compared with no aspirin use, aspirin use of more than 14 tablets per week was associated with a lower risk of BRAF–wild-type cancer (multivariable HR, 0.43; 95% CI, 0.25 to 0.75; age-adjusted incidence RD, −19.8; 95% CI, −26.3 to −13.3 per 100 000 person-years). The relationship between the number of aspirin tablets per week and colorectal cancer risk differed significantly by BRAF mutation status (P for heterogeneity = .005).

Conclusions and Relevance Regular aspirin use was associated with lower risk of BRAF–wild-type colorectal cancer but not with BRAF-mutated cancer risk. These findings suggest that BRAF-mutant colon tumor cells may be less sensitive to the effect of aspirin. Given the modest absolute risk difference, further investigations are necessary to determine clinical implications of our findings.

Colorectal cancer is a leading cause of cancer-related mortality worldwide. Randomized controlled trials have demonstrated that aspirin use reduces the risk of colorectal neoplasia,1,2 including the risk of colorectal cancer in individuals with Lynch syndrome.3 Aspirin is an inhibitor of prostaglandin-endoperoxide synthase 2 (PTGS2, alias cyclooxygenase 2), a key mediator of inflammatory responses.4 We have previously shown that aspirin use is associated with a lower risk of colorectal cancer with PTGS2 overexpression.5 However, since colorectal cancer represents a complex disease that cannot be explained by a single biomarker,6 the association of aspirin with various tumorigenic processes requires further investigation, which may help develop effective preventive strategies.7

Colorectal cancers develop through accumulation of genetic and epigenetic alterations and through tumor-host interactions (including immune and inflammatory reactions) in the tumor microenvironment.8,9BRAF is a member of the RAF kinase family, and an important regulator of the mitogen-activated protein kinase (MAPK) pathway.810 Activating mutations in the BRAF oncogene are observed in approximately 10% to 15% of colorectal cancers.8,9 Experimental evidence suggests that RAF-MAPK signaling plays an important role in up-regulation of PTGS2 activity and prostaglandin E2 synthesis.11,12 Considering that oncogenic BRAFmutation causes constitutive activation of RAF-MAPK signaling, we hypothesized that BRAF-mutant colonic cells might be less sensitive to the antitumor effects of aspirin, whereas BRAF–wild-type neoplastic cells might be more susceptible to its antitumor effects.

To test this hypothesis, we examined the association of aspirin use with the risk of colorectal cancer according to BRAF mutation status within 2, large, US nationwide prospective cohort studies that provided detailed and updated information on aspirin use. Because of the close relationship among RAF, RAS, and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), we additionally examined the association between regular aspirin use and incident colorectal cancer according to BRAF mutation status in strata of PTGS2 expression, PIK3CA mutation, and KRAS mutation status. As an exploratory analysis, we examined patient survival according to postdiagnosis aspirin use and BRAF mutation status.

Study Population

The Nurses' Health Study (NHS) was established in 1976 as a prospective cohort of 121 701 US registered female nurses who were aged 30 to 55 years at enrollment. The Health Professionals Follow-up Study (HPFS) was initiated in 1986 as a prospective cohort of 51 529 US male health professionals who were aged 40 to 75 years.13 Biennial questionnaires were used to update data on lifestyle factors. Based on the self-report, demographic characteristics including ethnicity were assessed. Ninety-eight percent of the NHS and 95% of the HPFS participants were non-Hispanic white.

Informed consent was obtained from all participants. This study was approved by Human Subjects Committees at Harvard School of Public Health and Brigham and Women's Hospital.

Assessment of Aspirin Use

We have previously published a detailed description of the collection of information on aspirin use and the definition of regular aspirin use in these cohorts.5 Briefly, in the NHS, aspirin use was first assessed in 1980 and every 2 years thereafter, except in 1986. The NHS participants were asked whether they took aspirin in most weeks, the number of tablets taken per week, and years of aspirin usage. We updated the information on the number of aspirin tablets taken per week (in categories) every 2 years. In the NHS, regular aspirin users were defined as women who reported consumption of 2 or more aspirin tablets per week and nonusers as women who used fewer than 2 tablets per week or no aspirin.

In the HPFS, in 1986 and every 2 years thereafter, participants were asked whether they used aspirin 2 or more times per week. Beginning in 1992, the mean number of tablets taken per week was assessed. In the HPFS, regular aspirin users were defined as men who reported consumption of aspirin at least 2 times per week and nonusers as men who consumed fewer than 2 times per week or no aspirin.

For both cohorts, participants were specifically asked about standard-dose (325 mg) aspirin tablets. Beginning in 1992, to reflect secular trends in aspirin use, participants were also asked to convert intake of 4 baby (81 mg) aspirin to 1 standard aspirin tablet in their responses. Aspirin dose was assessed using cumulative mean of tablets per week, which was the mean of all available data up to the start of each 2-year follow-up interval. We further evaluated duration of regular aspirin use (in years).5 As previously described,14 the major reasons for aspirin use among women were headache, arthritis and other musculoskeletal pain, and cardiovascular disease prevention. Among men, the major reasons were cardiovascular disease prevention, musculoskeletal pain, cardiovascular disease, and headache.

Assessment of Colorectal Cancer Cases

Incident colorectal cancer cases were ascertained by biennial questionnaire, the use of the National Death Index, and medical record review. Study physicians, unaware of exposure information, reviewed medical and pathological records to retrieve information on tumor location and disease stage. Considering the colorectal continuum model,15,16 we combined rectal and colon cancers to maximize statistical power.

We collected available tumor specimens from pathology laboratories across the United States. As previously reported, the baseline characteristics of participants with colorectal cancer with available tissue molecular data were similar to those of participants without available molecular data.17 A single pathologist (S.O.) reviewed tumor tissue slides and recorded pathological features.

BRAF, KRAS, PIK3CA, and Other Tumor Molecular Analyses

DNA was extracted from paraffin-embedded archival tumor tissue.13 Polymerase chain reaction and Pyrosequencing were performed for BRAF (HGNC: 1097; GenBank NM_004333) codon 600,18KRAS (HGNC: 6407; GenBank NM_033360) codons 12 and 13,19 and PIK3CA (HGNC: 8975; GenBank NM_006218) exons 9 and 20.20 Microsatellite instability, CpG island methylator phenotype, and LINE-1 methylation, which were used in survival analysis models, were assessed as previously described.2124

Immunohistochemistry for PTGS2 Expression

Prostaglandin-endoperoxide synthase 2 immunohistochemistry was performed using anti-PTGS2 (cyclooxygenase 2) antibody (Cayman Chemical; dilution 1:300), as previously described.5 A single investigator (S.O.), unaware of other data, interpreted tumor PTGS2 expression level (absent, weak, moderate, or strong), compared with adjacent normal colonic epithelium. A random sample of 124 cancers was examined by a second investigator (T.M.), and concordance between the 2 observers was 0.85 (κ = 0.69, P < .001).

Statistical Analysis

A detailed description of the statistical analysis, including our analysis of cancer mortality, is provided in the eSupplement. We used SAS software version 9.2 (SAS Institute Inc) for all statistical analyses. All P values were 2-sided and a P value <.05 was considered statistically significant. We included participants who provided baseline data on aspirin use in 1980 for the NHS and in 1986 for the HPFS. We excluded participants with a history of cancer (except for nonmelanoma skin cancer), inflammatory bowel disease, or familial polyposis at baseline. We followed up participants from the date of return of the baseline questionnaire, through July 1, 2006, for cancer incidence analysis, and through January 1, 2012, for cancer mortality analysis. Participants who died from causes other than colorectal cancer were censored.

To examine differential associations of aspirin use with colorectal cancer risk by tumor molecular subtype, we used Cox proportional cause-specific hazards regression model with a duplication method for competing risks data. This method permits estimation of separate associations of a risk factor (ie, aspirin use) with each tumor subtype, and has been used to assess whether a risk factor has statistically different regression coefficients for different tumor subtypes.5,25

In incidence analysis of one subtype, incidence of the other tumor subtype or tumor of unknown subtype was treated as censored data. A test of heterogeneity was conducted using a likelihood ratio test that compared the model that allowed for different associations of aspirin use according to tumor subtype, with a model that assumed a common association. Trend tests across categories of aspirin dose, and duration of regular use, were performed by assigning median values for these categories and treating the variables as continuous terms in the model. All analyses were stratified by age (in months), sex (in the combined cohort analysis), and calendar year of the questionnaire cycle.

Multivariable HRs were further adjusted for body mass index, family history of colorectal cancer in any first-degree relative, smoking status, lower endoscopy status, postmenopausal hormone use (for women only), history of diabetes, history of cardiovascular disease, physical activity, red meat intake, alcohol consumption, total caloric intake, folate intake, calcium intake, and current multivitamin use. Because information on other relevant medications (cholesterol-lowering drugs, antihypertensive drugs, and nonsteroidal anti-inflammatory drugs) was comprehensively collected beginning in 1990 onward in the NHS, we conducted a sensitivity analysis using data from 1990 for the NHS, and from 1986 for the HPFS to include these factors in our multivariable model. We used the most updated available information for all variables prior to each 2-year follow-up period, and modeled all variables as time-varying variables to take into account potential changes over follow-up time. If participants missed aspirin or other covariates information in biennial questionnaires, we used most recent available information from the past questionnaires.

Aspirin Use and Colorectal Cancer Risk by BRAF Status

At the baseline, there were 82 095 women in the NHS in 1980 and 45 770 men in the HPFS in 1986. Table 1 shows the demographic characteristics of the participants in 1994 according to regular aspirin use status. During 28 years and 3 165 985 person-years of follow-up, we documented 1226 incident cases of colorectal cancer (41% of all colorectal cancer cases) with available tissue molecular data. As previously reported,5 both women and men who used aspirin regularly had a significantly lower overall risk of colorectal cancer compared with nonusers (Table 2). Multivariable-adjusted models yielded similar risk estimates to age-adjusted models.

Table Graphic Jump LocationTable 1. Age-Adjusted Demographic Characteristics According to Regular Aspirin Use Status in 1994a
Table Graphic Jump LocationTable 2. Regular Use of Aspirin and Incident Colorectal Cancer by BRAF Mutation Statusa

For BRAF–wild-type cancer, age-adjusted incidence rates per 100 000 person-years were 40.2 (95% CI, 38.4 to 42.0) among nonusers and 30.5 (95% CI, 28.2 to 32.9) among regular aspirin users. Regular aspirin use was associated with a significantly lower risk of BRAF–wild-type cancer (multivariable HR, 0.73; 95% CI, 0.64 to 0.83; age-adjusted incidence rate difference [RD], −9.7; 95% CI, −12.6 to −6.7 per 100 000 person-years). For BRAF-mutated cancer, age-adjusted incidence rates per 100 000 person-years were 5.0 (95% CI, 4.4 to 5.6) among nonusers and 5.7 (95% CI, 4.9 to 6.5) among regular aspirin users. Regular aspirin use was not associated with a lower risk of BRAF-mutated cancer (multivariable HR, 1.03; 95% CI, 0.76 to 1.38; age-adjusted incidence RD, 0.7; 95% CI, −0.3 to 1.7 per 100 000 person-years). The association of aspirin use with colorectal cancer risk differed significantly according to BRAF mutation status (P for heterogeneity = .037). In a sensitivity analysis that included use of cholesterol-lowering drugs, antihypertensive drugs, and nonsteroidal anti-inflammatory drugs in the multivariable model, we found that inclusion of the medication data in the model did not substantially alter the results (eTable 1).

We observed a lower risk of BRAF–wild-type cancer with increasing aspirin tablets per week (P for trend<.001); however, we did not observe a significant trend in risk reduction for BRAF-mutated cancer (P for trend = .62; Table 3). The association of aspirin tablets per week with cancer risk differed significantly by BRAF mutation status (P for heterogeneity = .005). Compared with individuals who reported no aspirin use (age-adjusted incidence rate, 36.6; 95% CI, 34.4 to 38.7 per 100 000 person-years), a significantly lower risk of BRAF –wild-type cancer was observed among individuals who used 6 to 14 tablets of aspirin per week (age-adjusted incidence rates, 26.8; 95% CI, 24.1 to 29.4 per 100 000 person-years; multivariable HR, 0.70; 95% CI, 0.55 to 0.88; age-adjusted incidence RD, −9.8; 95% CI, −13.2 to −6.4 per 100 000 person-years) and among those who used more than 14 tablets of aspirin per week (age-adjusted incidence rate, 16.8; 95% CI, 10.7 to 22.9 per 100 000 person-years; multivariable HR, 0.43; 95% CI, 0.25 to 0.75; age-adjusted incidence RD, −19.8; 95% CI, −26.3 to −13.3 per 100 000 person-years).

Table Graphic Jump LocationTable 3. Aspirin Tablets per Week and Incident Colorectal Cancer by BRAF Mutation Statusa

We further examined the association between duration of regular aspirin use and colorectal cancer risk by BRAF mutation status (Table 4). Longer duration of aspirin use was associated with significant risk reduction for BRAF–wild-type cancer (P for trend <.001), whereas duration of aspirin use was not significantly associated with BRAF-mutated cancer risk (P for trend = .37). However, a formal test for heterogeneity of the association according to BRAF mutation status did not reach statistical significance (P for heterogeneity = .17).

Table Graphic Jump LocationTable 4. Duration of Regular Aspirin Use and Incident Colorectal Cancer by BRAF Mutation Statusa
Aspirin and Cancer Risk According to Combined Tumor Subtype

In an earlier study using these cohorts,5 we demonstrated that regular aspirin use was associated with a lower risk of PTGS2-positive cancer but not with PTGS2-negative cancer risk. We evaluated the association between aspirin use and BRAF–wild-type cancer risk by strata of tumor PTGS2 expression (Table 5). Regular aspirin use was associated with a significantly lower risk of BRAF–wild-type PTGS2-positive cancer (multivariable HR, 0.67; 95% CI, 0.56 to 0.81; age-adjusted incidence RD, −7.2; 95% CI, −9.7 to −4.6 per 100 000 person-years). These data suggest that the association between aspirin use and a lower risk of BRAF–wild-type cancer is primarily confined to tumors positive for PTGS2.

Table Graphic Jump LocationTable 5. Regular Use of Aspirin and Incident Colorectal Cancer by PTGS2 Status and Combination of BRAF-PTGS2 Statusa

In the analysis of combined BRAF-PIK3CA mutation status, regular aspirin use appeared to be associated with a lower risk of BRAF–wild-type cancer, regardless of PIK3CA mutation status (eTable 2). Moreover, the association between regular aspirin use and a lower risk of BRAF–wild-type cancer appeared to be independent of KRAS mutation status (eTable 3).

Postdiagnosis Aspirin Use and Patient Survival According to BRAF Status

We did not observe significant interaction between postdiagnosis aspirin use and BRAF mutation status in cancer-specific or overall survival analysis (eTable 4). Further analysis of survival among patients with colorectal cancer according to postdiagnosis aspirin use and combined BRAF and PIK3CA mutation status had limited statistical power (eTable 4).

In 2 large prospective cohort studies, we found that regular aspirin use was associated with a lower risk of BRAF–wild-type colorectal cancer, but not with BRAF-mutated cancer risk. The lower BRAF–wild-type cancer risk was more pronounced with increasing aspirin tablets per week. Furthermore, the association of aspirin use with lower cancer risk appeared to be most evident for BRAF–wild-type PTGS2-positive cancer, whereas aspirin use was not associated with BRAF-mutated cancer regardless of tumor PTGS2 expression status. These findings support the hypothesis that BRAF-mutated cells may show resistance to the anticancer effects of aspirin due to up-regulation of the MAPK pathway. Previous experimental studies have shown that activating BRAF mutation results in MAPK-mediated up-regulation of PTGS2, and prostaglandin E2 production.11,12,26 Considering that BRAF mutation might constitutively up-regulate PTGS2 activity, we speculate that, within BRAF-mutant neoplastic cells, PTGS2 may be persistently active even with low expression level, potentially conferring resistance to the effect of aspirin. In contrast, within BRAF–wild-type cells, PTGS2 activity may be relatively inducible and overexpression of PTGS2 may function as a marker of a tumor cell that may be more susceptible to the effects of aspirin. The exact mechanisms underlying the interplay of aspirin, PTGS2, and BRAF mutation need to be elucidated by further investigations.

There was no statistically significant interaction between postdiagnosis aspirin use and BRAF mutation status in colorectal cancer-specific or overall survival analysis. This suggests that the potential protective effect of aspirin may differ by BRAF status in the early phase of tumor evolution before clinical detection but not during later phases of tumor progression. One reason for these seemingly discrepant findings in cancer incidence analysis compared with cancer survival analysis may be related to differences in the effect of aspirin according to tumor microenvironmental changes. During tumor evolution, colonic cells encounter multifactorial molecular events, including changes in genome, epigenome, proteome, metabolome, and interactome. Thus, the interactive effect of aspirin use and tumor molecular characteristics might vary as a tumor's microenvironment evolves.

The association between regular aspirin use and a lower risk of BRAF–wild-type cancer appeared independent of PIK3CA and KRAS mutation status. Together with our previous data,13 the interplay between aspirin and PIK3CA mutation status may be operative in later phases rather than earlier phases of tumor evolution.

The identification of specific cancer subtypes that are prevented by aspirin is important for several reasons.7,27 First, it enhances our understanding of the molecular pathogenesis of colorectal neoplasia and the mechanisms through which aspirin may exert its antineoplastic effects. Second, development of clinical, genetic, or molecular predictors of specific subtypes of colorectal cancer might lead to the development of more tailored screening or chemopreventive strategies. Nevertheless, given the modest absolute risk difference, further investigations are necessary to evaluate clinical implications of our findings. Lastly, our data provide additional support for a causal association between aspirin use and risk reduction for a specific subtype of colorectal cancers. Accumulating evidence supports preventive effect of aspirin against colorectal cancer.13,2830 The findings of clinical studies in Lynch syndrome mutation carriers further support our results because the vast majority of cancers associated with Lynch syndrome are BRAF–wild-type.31

Several attributes of the NHS and the HPFS cohorts strengthen our study and its findings. First, because updated information on aspirin use was prospectively collected over 28 years, we were able to assess the long-term association of aspirin exposure with colorectal cancer, which can take many years to evolve. Second, our detailed, updated exposure data allowed us to control for the effects of potential confounding by other dietary and lifestyle factors implicated in colorectal carcinogenesis. Third, our present study exploits a molecular pathological epidemiology analytic approach,8,32 which has enabled us to elucidate the association between a specific exposure and molecular subtype of cancer, to provide better insight into disease pathogenesis.13,3340

Our study has limitations. The possibility of residual confounding by measured or unmeasured factors cannot be excluded. Although colorectal cancer case ascertainment was well established in our cohorts, we were not able to retrieve tissue specimens from all incident cancers. Statistical power was limited, especially in the analysis of the number of aspirin tablets per week, due to BRAF mutations present in only approximately 10% to 15% of colorectal cancers.10,15,4143 The vast majority of participants were non-Hispanic white, and our findings may not be generalizable to other ethnic groups. Although our current study represented a hypothesis-driven analysis, we are aware of the various caveats associated with molecular pathological epidemiology and tumor subtype analyses.8,32 Our results must be validated by independent studies, and further investigations are necessary to confirm the association of aspirin use with a lower risk of BRAF–wild-type cancer independent of other tumor markers.

In summary, regular aspirin use was associated with lower risk of BRAF–wild-type colorectal cancer but not with BRAF-mutated cancer risk. Nevertheless, given the modest absolute risk difference, further investigations are necessary to determine clinical implications of our findings.

Corresponding Authors: Andrew T. Chan, MD, MPH, Division of Gastroenterology, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114 (achan@partners.org); Shuji Ogino, MD, PhD, MS, Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, 450 Brookline Ave, Boston, MA 02215 (shuji_ogino@dfci.harvard.edu).

AuthorContributions: Drs Nishihara and Chan had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Drs Nishihara, Lochhead, Kuchiba, and Jung contributed equally. Drs Chan and Ogino contributed equally.

Study concept and design: Giovannucci, Fuchs, Chan, Ogino.

Acquisition of data: Nishihara, Lochhead, Kuchiba, Jung, Yamauchi, Liao, Imamura, Qian, Morikawa, Wang, Spiegelman, Cho, Giovannucci, Fuchs, Chan, Ogino.

Analysis and interpretation of data: Nishihara, Lochhead, Kuchiba, Jung, Wang, Spiegelman, Cho, Giovannucci, Fuchs, Chan, Ogino.

Drafting of the manuscript: Nishihara, Lochhead, Jung, Imamura, Wang, Cho, Fuchs, Chan, Ogino.

Critical revision of the manuscript for important intellectual content: Nishihara, Lochhead, Kuchiba, Yamauchi, Liao, Qian, Morikawa, Spiegelman, Cho, Giovannucci, Fuchs, Chan, Ogino.

Statistical analysis: Nishihara, Kuchiba, Jung, Liao, Wang, Spiegelman, Cho, Fuchs, Chan, Ogino.

Obtained funding: Cho, Giovannucci, Fuchs, Chan, Ogino.

Administrative, technical, or material support: Lochhead, Jung, Imamura, Qian, Cho, Giovannucci, Fuchs, Chan, Ogino.

Study supervision: Cho, Fuchs, Chan, Ogino.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Chan reported that he has previously served as a consultant for Bayer Healthcare, Millennium Pharmaceuticals, Pfizer Inc, and Pozen Inc. This study was not funded by Bayer Healthcare, Millennium Pharmaceuticals, Pfizer Inc, or Pozen Inc. No other conflicts of interest were reported.

Funding/Support:This work was supported by grants P01 CA87969 to Dr Hankinson; P01 CA55075 and UM1 CA167552 to Dr Willett; P50 CA127003 to Dr Fuchs.; R01 CA137178 and K24 DK098311 to Dr Chan; and R01 CA151993 to Dr Ogino from the National Institutes of Health (NIH); the Bennett Family Fund for Targeted Therapies Research; and the National Colorectal Cancer Research Alliance. Dr Lochhead is a Scottish Government Clinical Academic Fellow and was supported by a Harvard University Frank Knox Memorial Fellowship. Dr Chan is a Damon Runyon Clinical Investigator.

Role of the Sponsor: The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of NIH or the Damon Runyon Cancer Research Foundation.

Additional Contributions: We deeply thank participants of the Nurses' Health Study and the Health Professionals Follow-up Study who provided us with information through questionnaires, and biological specimens. We are grateful to hospitals and pathology departments throughout the United States for generously providing us with tissue specimens. In addition, we would like to thank the staff of the Nurses' Health Study and the Health Professionals Follow-Up Study for their valuable contributions, the state cancer registries for their help: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Maryland, Maine, Michigan, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Virginia, Washington, Wyoming.

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PubMed   |  Link to Article
Ogino S, Nosho K, Kirkner GJ,  et al.  CpG island methylator phenotype, microsatellite instability, BRAF mutation and clinical outcome in colon cancer.  Gut. 2009;58(1):90-96
PubMed   |  Link to Article
Nosho K, Irahara N, Shima K,  et al.  Comprehensive biostatistical analysis of CpG island methylator phenotype in colorectal cancer using a large population-based sample.  PLoS One. 2008;3(11):e3698
PubMed   |  Link to Article
Ogino S, Nosho K, Kirkner GJ,  et al.  A cohort study of tumoral LINE-1 hypomethylation and prognosis in colon cancer.  J Natl Cancer Inst. 2008;100(23):1734-1738
PubMed   |  Link to Article
Irahara N, Nosho K, Baba Y,  et al.  Precision of pyrosequencing assay to measure LINE-1 methylation in colon cancer, normal colonic mucosa, and peripheral blood cells.  J Mol Diagn. 2010;12(2):177-183
PubMed   |  Link to Article
Ogino S, Nishihara R, Lochhead P,  et al.  Prospective study of family history and colorectal cancer risk by tumor LINE-1 methylation level.  J Natl Cancer Inst. 2013;105(2):130-140
PubMed   |  Link to Article
Chang MS, Chen BC, Weng CM, Lee WS, Lin CH. Involvement of Ras/Raf-1/p44/42 MAPK in YC-1-induced cyclooxygenase-2 expression in human pulmonary epithelial cells.  Pharmacol Res. 2009;60(4):247-253
PubMed   |  Link to Article
Chia WK, Ali R, Toh HC. Aspirin as adjuvant therapy for colorectal cancer—reinterpreting paradigms.  Nat Rev Clin Oncol. 2012;9(10):561-570
PubMed   |  Link to Article
Rothwell PM, Price JF, Fowkes FG,  et al.  Short-term effects of daily aspirin on cancer incidence, mortality, and non-vascular death: analysis of the time course of risks and benefits in 51 randomised controlled trials.  Lancet. 2012;379(9826):1602-1612
PubMed   |  Link to Article
Dubé C, Rostom A, Lewin G,  et al; US Preventive Services Task Force.  The use of aspirin for primary prevention of colorectal cancer: a systematic review prepared for the US Preventive Services Task Force.  Ann Intern Med. 2007;146(5):365-375
PubMed   |  Link to Article
Bosetti C, Rosato V, Gallus S, Cuzick J, La Vecchia C. Aspirin and cancer risk: a quantitative review to 2011.  Ann Oncol. 2012;23(6):1403-1415
PubMed   |  Link to Article
Funkhouser WK Jr, Lubin IM, Monzon FA,  et al.  Relevance, pathogenesis, and testing algorithm for mismatch repair-defective colorectal carcinomas: a report of the association for molecular pathology.  J Mol Diagn. 2012;14(2):91-103
PubMed   |  Link to Article
Ogino S, Stampfer M. Lifestyle factors and microsatellite instability in colorectal cancer: the evolving field of molecular pathological epidemiology.  J Natl Cancer Inst. 2010;102(6):365-367
PubMed   |  Link to Article
Razzak AA, Oxentenko AS, Vierkant RA,  et al.  Associations between intake of folate and related micronutrients with molecularly defined colorectal cancer risks in the Iowa Women's Health Study.  Nutr Cancer. 2012;64(7):899-910
PubMed   |  Link to Article
Gay LJ, Mitrou PN, Keen J,  et al.  Dietary, lifestyle and clinicopathological factors associated with APC mutations and promoter methylation in colorectal cancers from the EPIC-Norfolk study.  J Pathol. 2012;228(3):405-415
PubMed   |  Link to Article
Curtin K, Samowitz WS, Ulrich CM,  et al.  Nutrients in folate-mediated, one-carbon metabolism and the risk of rectal tumors in men and women.  Nutr Cancer. 2011;63(3):357-366
PubMed   |  Link to Article
Shigaki H, Baba Y, Watanabe M,  et al.  LINE-1 hypomethylation in noncancerous esophageal mucosae is associated with smoking history.  Ann Surg Oncol. 2012;19(13):4238-4243
PubMed   |  Link to Article
Hughes LA, Simons CC, van den Brandt PA,  et al.  Body size, physical activity and risk of colorectal cancer with or without the CpG island methylator phenotype (CIMP).  PLoS One. 2011;6(4):e18571
PubMed   |  Link to Article
Rosty C, Young JP, Walsh MD,  et al.  Colorectal carcinomas with KRAS mutation are associated with distinctive morphological and molecular features.  Mod Pathol. 2013;26(6):825-834
PubMed   |  Link to Article
Buchanan DD, Win AK, Walsh MD,  et al.  Family history of colorectal cancer in BRAF p.V600E-mutated colorectal cancer cases.  Cancer Epidemiol Biomarkers Prev. 2013;22(5):917-926
PubMed   |  Link to Article
Burnett-Hartman AN, Newcomb PA, Potter JD,  et al.  Genomic aberrations occurring in subsets of serrated colorectal lesions but not conventional adenomas.  Cancer Res. 2013;73(9):2863-2872
PubMed   |  Link to Article
Popovici V, Budinska E, Tejpar S,  et al.  Identification of a poor-prognosis BRAF-mutant-like population of patients with colon cancer.  J Clin Oncol. 2012;30(12):1288-1295
PubMed   |  Link to Article
Gavin PG, Colangelo LH, Fumagalli D,  et al.  Mutation profiling and microsatellite instability in stage II and III colon cancer: an assessment of their prognostic and oxaliplatin predictive value.  Clin Cancer Res. 2012;18(23):6531-6541
PubMed   |  Link to Article
Zlobec I, Bihl M, Foerster A, Rufle A, Lugli A. Comprehensive analysis of CpG island methylator phenotype (CIMP)-high, -low, and -negative colorectal cancers based on protein marker expression and molecular features.  J Pathol. 2011;225(3):336-343
PubMed   |  Link to Article

Figures

Tables

Table Graphic Jump LocationTable 1. Age-Adjusted Demographic Characteristics According to Regular Aspirin Use Status in 1994a
Table Graphic Jump LocationTable 2. Regular Use of Aspirin and Incident Colorectal Cancer by BRAF Mutation Statusa
Table Graphic Jump LocationTable 3. Aspirin Tablets per Week and Incident Colorectal Cancer by BRAF Mutation Statusa
Table Graphic Jump LocationTable 4. Duration of Regular Aspirin Use and Incident Colorectal Cancer by BRAF Mutation Statusa
Table Graphic Jump LocationTable 5. Regular Use of Aspirin and Incident Colorectal Cancer by PTGS2 Status and Combination of BRAF-PTGS2 Statusa

References

Flossmann E, Rothwell PM.British Doctors Aspirin Trial and the UK-TIA Aspirin Trial.  Effect of aspirin on long-term risk of colorectal cancer: consistent evidence from randomised and observational studies.  Lancet. 2007;369(9573):1603-1613
PubMed   |  Link to Article
Rothwell PM, Wilson M, Elwin CE,  et al.  Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials.  Lancet. 2010;376(9754):1741-1750
PubMed   |  Link to Article
Burn J, Gerdes AM, Macrae F,  et al; CAPP2 Investigators.  Long-term effect of aspirin on cancer risk in carriers of hereditary colorectal cancer: an analysis from the CAPP2 randomised controlled trial.  Lancet. 2011;378(9809):2081-2087
PubMed   |  Link to Article
Wang D, Xia D, DuBois RN. The crosstalk of PTGS2 and EGF signaling pathways in colorectal cancer.  Cancers. 2011;3(4):3894-3908
Link to Article
Chan AT, Ogino S, Fuchs CS. Aspirin and the risk of colorectal cancer in relation to the expression of COX-2.  N Engl J Med. 2007;356(21):2131-2142
PubMed   |  Link to Article
Ogino S, Fuchs CS, Giovannucci E. How many molecular subtypes? implications of the unique tumor principle in personalized medicine.  Expert Rev Mol Diagn. 2012;12(6):621-628
PubMed   |  Link to Article
Thun MJ, Jacobs EJ, Patrono C. The role of aspirin in cancer prevention.  Nat Rev Clin Oncol. 2012;9(5):259-267
PubMed   |  Link to Article
Ogino S, Chan AT, Fuchs CS, Giovannucci E. Molecular pathological epidemiology of colorectal neoplasia: an emerging transdisciplinary and interdisciplinary field.  Gut. 2011;60(3):397-411
PubMed   |  Link to Article
Lao VV, Grady WM. Epigenetics and colorectal cancer.  Nat Rev Gastroenterol Hepatol. 2011;8(12):686-700
PubMed   |  Link to Article
Phipps AI, Buchanan DD, Makar KW,  et al.  BRAF mutation status and survival after colorectal cancer diagnosis according to patient and tumor characteristics.  Cancer Epidemiol Biomarkers Prev. 2012;21(10):1792-1798
PubMed   |  Link to Article
Wagner EF, Nebreda AR. Signal integration by JNK and p38 MAPK pathways in cancer development.  Nat Rev Cancer. 2009;9(8):537-549
PubMed   |  Link to Article
Sumimoto H, Imabayashi F, Iwata T, Kawakami Y. The BRAF-MAPK signaling pathway is essential for cancer-immune evasion in human melanoma cells.  J Exp Med. 2006;203(7):1651-1656
PubMed   |  Link to Article
Liao X, Lochhead P, Nishihara R,  et al.  Aspirin use, tumor PIK3CA mutation, and colorectal-cancer survival.  N Engl J Med. 2012;367(17):1596-1606
PubMed   |  Link to Article
Chan AT, Ogino S, Fuchs CS. Aspirin use and survival after diagnosis of colorectal cancer.  JAMA. 2009;302(6):649-658
PubMed   |  Link to Article
Yamauchi M, Morikawa T, Kuchiba A,  et al.  Assessment of colorectal cancer molecular features along bowel subsites challenges the conception of distinct dichotomy of proximal versus distal colorectum.  Gut. 2012;61(6):847-854
PubMed   |  Link to Article
Yamauchi M, Lochhead P, Morikawa T,  et al.  Colorectal cancer: a tale of two sides or a continuum?  Gut. 2012;61(6):794-797
PubMed   |  Link to Article
Morikawa T, Kuchiba A, Yamauchi M,  et al.  Association of CTNNB1 (beta-catenin) alterations, body mass index, and physical activity with survival in patients with colorectal cancer.  JAMA. 2011;305(16):1685-1694
PubMed   |  Link to Article
Ogino S, Kawasaki T, Kirkner GJ, Loda M, Fuchs CS. CpG island methylator phenotype-low (CIMP-low) in colorectal cancer: possible associations with male sex and KRAS mutations.  J Mol Diagn. 2006;8(5):582-588
PubMed   |  Link to Article
Ogino S, Kawasaki T, Brahmandam M,  et al.  Sensitive sequencing method for KRAS mutation detection by Pyrosequencing.  J Mol Diagn. 2005;7(3):413-421
PubMed   |  Link to Article
Liao X, Morikawa T, Lochhead P,  et al.  Prognostic role of PIK3CA mutation in colorectal cancer: cohort study and literature review.  Clin Cancer Res. 2012;18(8):2257-2268
PubMed   |  Link to Article
Ogino S, Nosho K, Kirkner GJ,  et al.  CpG island methylator phenotype, microsatellite instability, BRAF mutation and clinical outcome in colon cancer.  Gut. 2009;58(1):90-96
PubMed   |  Link to Article
Nosho K, Irahara N, Shima K,  et al.  Comprehensive biostatistical analysis of CpG island methylator phenotype in colorectal cancer using a large population-based sample.  PLoS One. 2008;3(11):e3698
PubMed   |  Link to Article
Ogino S, Nosho K, Kirkner GJ,  et al.  A cohort study of tumoral LINE-1 hypomethylation and prognosis in colon cancer.  J Natl Cancer Inst. 2008;100(23):1734-1738
PubMed   |  Link to Article
Irahara N, Nosho K, Baba Y,  et al.  Precision of pyrosequencing assay to measure LINE-1 methylation in colon cancer, normal colonic mucosa, and peripheral blood cells.  J Mol Diagn. 2010;12(2):177-183
PubMed   |  Link to Article
Ogino S, Nishihara R, Lochhead P,  et al.  Prospective study of family history and colorectal cancer risk by tumor LINE-1 methylation level.  J Natl Cancer Inst. 2013;105(2):130-140
PubMed   |  Link to Article
Chang MS, Chen BC, Weng CM, Lee WS, Lin CH. Involvement of Ras/Raf-1/p44/42 MAPK in YC-1-induced cyclooxygenase-2 expression in human pulmonary epithelial cells.  Pharmacol Res. 2009;60(4):247-253
PubMed   |  Link to Article
Chia WK, Ali R, Toh HC. Aspirin as adjuvant therapy for colorectal cancer—reinterpreting paradigms.  Nat Rev Clin Oncol. 2012;9(10):561-570
PubMed   |  Link to Article
Rothwell PM, Price JF, Fowkes FG,  et al.  Short-term effects of daily aspirin on cancer incidence, mortality, and non-vascular death: analysis of the time course of risks and benefits in 51 randomised controlled trials.  Lancet. 2012;379(9826):1602-1612
PubMed   |  Link to Article
Dubé C, Rostom A, Lewin G,  et al; US Preventive Services Task Force.  The use of aspirin for primary prevention of colorectal cancer: a systematic review prepared for the US Preventive Services Task Force.  Ann Intern Med. 2007;146(5):365-375
PubMed   |  Link to Article
Bosetti C, Rosato V, Gallus S, Cuzick J, La Vecchia C. Aspirin and cancer risk: a quantitative review to 2011.  Ann Oncol. 2012;23(6):1403-1415
PubMed   |  Link to Article
Funkhouser WK Jr, Lubin IM, Monzon FA,  et al.  Relevance, pathogenesis, and testing algorithm for mismatch repair-defective colorectal carcinomas: a report of the association for molecular pathology.  J Mol Diagn. 2012;14(2):91-103
PubMed   |  Link to Article
Ogino S, Stampfer M. Lifestyle factors and microsatellite instability in colorectal cancer: the evolving field of molecular pathological epidemiology.  J Natl Cancer Inst. 2010;102(6):365-367
PubMed   |  Link to Article
Razzak AA, Oxentenko AS, Vierkant RA,  et al.  Associations between intake of folate and related micronutrients with molecularly defined colorectal cancer risks in the Iowa Women's Health Study.  Nutr Cancer. 2012;64(7):899-910
PubMed   |  Link to Article
Gay LJ, Mitrou PN, Keen J,  et al.  Dietary, lifestyle and clinicopathological factors associated with APC mutations and promoter methylation in colorectal cancers from the EPIC-Norfolk study.  J Pathol. 2012;228(3):405-415
PubMed   |  Link to Article
Curtin K, Samowitz WS, Ulrich CM,  et al.  Nutrients in folate-mediated, one-carbon metabolism and the risk of rectal tumors in men and women.  Nutr Cancer. 2011;63(3):357-366
PubMed   |  Link to Article
Shigaki H, Baba Y, Watanabe M,  et al.  LINE-1 hypomethylation in noncancerous esophageal mucosae is associated with smoking history.  Ann Surg Oncol. 2012;19(13):4238-4243
PubMed   |  Link to Article
Hughes LA, Simons CC, van den Brandt PA,  et al.  Body size, physical activity and risk of colorectal cancer with or without the CpG island methylator phenotype (CIMP).  PLoS One. 2011;6(4):e18571
PubMed   |  Link to Article
Rosty C, Young JP, Walsh MD,  et al.  Colorectal carcinomas with KRAS mutation are associated with distinctive morphological and molecular features.  Mod Pathol. 2013;26(6):825-834
PubMed   |  Link to Article
Buchanan DD, Win AK, Walsh MD,  et al.  Family history of colorectal cancer in BRAF p.V600E-mutated colorectal cancer cases.  Cancer Epidemiol Biomarkers Prev. 2013;22(5):917-926
PubMed   |  Link to Article
Burnett-Hartman AN, Newcomb PA, Potter JD,  et al.  Genomic aberrations occurring in subsets of serrated colorectal lesions but not conventional adenomas.  Cancer Res. 2013;73(9):2863-2872
PubMed   |  Link to Article
Popovici V, Budinska E, Tejpar S,  et al.  Identification of a poor-prognosis BRAF-mutant-like population of patients with colon cancer.  J Clin Oncol. 2012;30(12):1288-1295
PubMed   |  Link to Article
Gavin PG, Colangelo LH, Fumagalli D,  et al.  Mutation profiling and microsatellite instability in stage II and III colon cancer: an assessment of their prognostic and oxaliplatin predictive value.  Clin Cancer Res. 2012;18(23):6531-6541
PubMed   |  Link to Article
Zlobec I, Bihl M, Foerster A, Rufle A, Lugli A. Comprehensive analysis of CpG island methylator phenotype (CIMP)-high, -low, and -negative colorectal cancers based on protein marker expression and molecular features.  J Pathol. 2011;225(3):336-343
PubMed   |  Link to Article
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