Is Physician Detection Associated With Thinner Melanomas? FREE

The incidence and mortality rates associated with primary cutaneous melanoma continue to increase in the United States.¹ In 1998, it is estimated that 41,600 individuals were diagnosed as having invasive melanoma, and that 7300 people died due to the disease.² Efforts to reverse these trends have focused on primary prevention through public awareness programs and sun exposure education.^3- 5 Yet, the current lifetime risk of an American developing malignant melanoma is expected to reach 1 in 75 by the year 2000.⁶

In the absence of regional and systemic metastasis, Breslow⁷ tumor thickness remains the most important prognostic indicator for predicting mortality and is strongly associated with survival. Early detection and excision of thin melanomas is associated with excellent patient survival.⁸ For secondary prevention to be successful, a tumor must be detected at an early stage of development and surgically treated.⁹ In this study, we examine differences in melanoma detection patterns and their relationship to melanoma thickness.

All patients with primary cutaneous melanoma who presented to the Melanoma Center at the Johns Hopkins Medical Institutions, Baltimore, Md, between June 1995 and June 1997 were interviewed and considered eligible for this study. Patients were examined and questioned by their treating physicians (J.R.L., S.B.G., and S.E.K.) as part of their clinical history. All patients were interviewed no more than 6 months after their initial diagnoses.

Patients were excluded from the study population if evidence showed systemic metastatic disease. These patients were excluded because signs or symptoms of regional or systemic metastases could confound the relationship between detection and thickness of the primary lesion. A total of 102 patients met our criteria and formed our study group.

During their evaluation at the Melanoma Center, patients were questioned specifically about who first detected their melanoma. Patients were queried about the interval of time between initial awareness of a suspicious pigmented lesion and the biopsy of the lesion by a physician. They were also interviewed on personal characteristics including age, education, and family or personal history of melanoma. The majority of biopsy specimens were reviewed by dermatopathologists at the Johns Hopkins Dermatopathology Division for histopathologic confirmation and measurement of tumor thickness.

Differences in personal characteristics (sex, detection pattern, and history of melanoma) were analyzed by univariate χ² analysis. When the analysis had low expected frequencies, a Fisher exact test was performed. Characteristics with ordered variables (age, education, time to biopsy) were studied using trend analysis. Personal and lesion characteristics were grouped according to median tumor thickness and compared using the Wilcoxon rank sum test. Analysis of tumor thickness by age and time to biopsy was completed using the nonparametric Kruskal-Wallis 1-way analysis of variance by ranks procedure. Tumor thickness was evaluated using χ² trend analysis after grouping lesions into the following categories: 0.75 mm or less, 0.76 to 1.50 mm, 1.51 to 4.00 mm, and greater than 4.00 mm. Finally, the variables that were significant in univariate analysis were tested for possible confounding and interactions using logistic regression analysis.

A total of 102 patients with primary cutaneous melanoma were analyzed, including 47 men (46%) and 55 women (54%). Two thirds of the patients had at least a college education, while 9% had not received a high school diploma. A total of 16 patients (16%) had a positive family history of melanoma, while 4 patients (4%) had a previous personal history of primary cutaneous melanoma.

Patients were carefully questioned regarding who first noticed their melanoma, and the results are tabulated according to detection pattern in Table 1. Detection was classified into the following categories: physicians, self-detection, spouses, and other individuals. Patients detected 55% of the melanomas in this study, while physicians found approximately 24% of the tumors. The remainder were divided between spouses (12%) and others (10%). There were significant differences in self-detection rates between men and women (40% vs 67%; P<.01). Among men, 12 (26%) of the 47 melanomas were identified by a spouse. However, among women none of the melanomas were identified by the spouse (0/55; P<.001).

Among men and women, similar percentages of melanomas were physician-detected (26% vs 22%). Patients with higher education (college or graduate school) were more likely to have melanomas detected by a physician than those with less education (32% vs 9%; P=.01). There were no identifiable differences by age or for patients with a personal or a family history of melanoma. Differences according to sex for self-detected lesions and according to education for physician-detected lesions were not explained by any of the other variables shown in Table 1.

There were identifiable trends based on the location of the melanoma. Of the lesions that were in a visible location to the patient (head, arms, legs, chest), 48 (70%) of 69 were self-detected; however, patients found only 8 (24%) of the 33 melanomas on the back or buttocks (P<.001). Using multiple logistic regression analysis, there were no sex differences in self-detection rates based on the location of the melanoma.

The median time to biopsy after initial detection of a suspicious lesion was 3 months (range, <1 week to 10 years). Among the lesions that were detected by physicians, a biopsy had been performed within a month in 83% of the cases, while in 4% of the cases a biopsy had not been performed before 6 months. For patient-detected lesions, a biopsy had been performed within a month in 16% of the cases, while in 45% of the cases a biopsy had not been performed earlier than 6 months after having been detected. Thus, physician-detected melanomas were more likely to undergo biopsy within a month than patient-detected lesions (83% vs 16%; P<.001).

Tumor thickness was analyzed in relation to personal and lesion characteristics. Older patient age was associated with thicker melanomas, with a median thickness of 1.6 mm in patients older than 60 years, compared with 0.49 mm (P=.002) in patients younger than 40 years. Patients with any college or graduate school education had a median tumor thickness of 0.4 mm, while patients with a high school education or less had a median tumor thickness of 1.3 mm (P<.001). In univariate analysis, a delay in biopsy of a suspicious lesion was associated with a thicker melanoma (P=.03).

Histopathologic data were obtained for each patient and are presented in Table 2. Of the physician-detected melanomas, 11 (46%) of 24 physician-found lesions were in situ, while 2 (8%) of 24 were greater than 1.50 mm in thickness. Of the patient-detected lesions, only 8 (14%) of 56 were in situ, while 19 (34%) of 56 were greater than 1.50 mm in tumor thickness. Using χ² trend analysis, we found that physician detection was associated with melanomas that were thinner than patient-detected melanomas (P=.005), or all nonphysician detected melanomas combined (P=.002). Melanomas were also analyzed according to Breslow⁷ thickness data. Physician-found melanomas had the lowest median tumor thickness (0.23 mm), compared with 0.9 mm (P<.001, Wilcoxon rank sum test) for self-detected melanomas, 0.75 mm (P=.03) for spouse-detected melanomas, and 0.9 mm (P<.001) for nonphysician groups combined.

To adjust for potential confounders, physician detection and tumor thickness were analyzed in the logistic regression model shown in Table 3. In unadjusted crude analysis, physician detection of a lesion was associated with a greater probability of discovering a thinner (≤0.75 mm) melanoma (relative risk, 4.17; P=.01). In adjusted analysis, physician detection (P=.04), age (P=.004), and education (P=.002) were associated with tumor thickness.

We assessed melanoma detection patterns to investigate the hypothesis that thinner lesions were more likely to have been physician detected. When compared with self-detected melanomas, the median tumor thickness was significantly less for physician-detected melanomas. The majority of prognostically favorable lesions⁸ (in situ and lesions <0.75 mm) were found by physicians. Using trend analysis, our results support the assertion that physicians identify melanomas at an earlier stage than do the patients themselves or all nonphysician groups combined.

Patients with at least a college education are more likely to have their melanomas detected by a physician, possibly because these patients seek medical advice more often. The majority of the easily visible lesions were patient-detected. There was a positive association between physician detection of a tumor and its immediate biopsy. In almost 85% of physician-detected melanomas, biopsies had been performed within a month, indicating that suspicious lesions were identified and removed expeditiously.

Using univariate analysis, we demonstrated that factors associated with a thinner tumor included younger patient age, higher educational level, and decreased time to biopsy. In univariate and multivariate logistic regression analysis, physician detection of a melanoma was associated with thinner tumors. Physician detection was associated with a 400% increase in the likelihood of discovering thinner melanomas (≤0.75 mm; relative risk, 4.17). After controlling for interactions, the study variables of age and education remained significant. Although time to biopsy was no longer significant in multivariate analysis, each month of delay in biopsy was associated with a 6% decrease in the likelihood of discovering thin melanomas (≤0.75 mm).

One limitation of our article is the inherent difficulty of accurately estimating and analyzing the time to biopsy. We divided time to biopsy into what we believed were relevant categories; however, these may not represent clinically important divisions. Because little is known about the growth rate of melanoma, we cannot determine whether the differences observed in the time to biopsy would contribute significantly to tumor thickness. In addition, we do not have long-term survival information for patients in our study. Since we have shown that physician detection is associated with thinner melanomas, we predict that this will result in improved survival.¹⁰ Finally, unmeasured confounding and a small sample size also may have had an important influence on this study.

Few studies have investigated differences in melanoma detection patterns. A study by Koh et al¹¹ of 216 patients designed to look at sex differences in melanoma detection revealed that women are more likely to discover their own lesions than men (66% vs 42%). Our results are similar. Sixty-seven percent of women and 40% of men detected their melanomas in our study group. Hersey et al¹² noted that thick primary melanomas were most likely to occur in men. However, we did not find a significant difference in melanoma thickness according to the sex of the patient.

In conclusion, we have described melanoma detection patterns in a screened population of patients at a tertiary referral center. Melanomas that were physician-detected were thinner than melanomas that were detected by nonphysicians. Future studies that include survival data can investigate differences in outcome according to melanoma detection patterns. However, routine skin examination for melanoma by all physicians may result in identification of lesions early enough to result in favorable outcomes.