Context Sexual activity has been hypothesized to play a role in the development
of prostate cancer, but epidemiological data are virtually limited to case-control
studies, which may be prone to bias because recall among individuals with
prostate cancer could be distorted as a consequence of prostate malignancy
or ongoing therapy.
Objective To examine the association between ejaculation frequency, which includes
sexual intercourse, nocturnal emission, and masturbation and risk of prostate
Design, Setting, and Participants Prospective study using follow-up data from the Health Professionals
Follow-up Study (February 1, 1992, through January 31, 2000) of 29 342
US men aged 46 to 81 years, who provided information on history of ejaculation
frequency on a self-administered questionnaire in 1992 and responded to follow-up
questionnaires every 2 years to 2000. Ejaculation frequency was assessed by
asking participants to report the average number of ejaculations they had
per month during the ages of 20 to 29 years, 40 to 49 years, and during the
past year (1991).
Main Outcome Measure Incidence of total prostate cancer.
Results During 222 426 person-years of follow-up, there were 1449 new cases
of total prostate cancer, 953 organ-confined cases, and 147 advanced cases
of prostate cancer. Most categories of ejaculation frequency were unrelated
to risk of prostate cancer. However, high ejaculation frequency was related
to decreased risk of total prostate cancer. The multivariate relative risks
for men reporting 21 or more ejaculations per month compared with men reporting
4 to 7 ejaculations per month at ages 20 to 29 years were 0.89 (95% confidence
interval [CI], 0.73-1.10); ages 40 to 49 years, 0.68 (95% CI, 0.53-0.86);
previous year, 0.49 (95% CI, 0.27-0.88); and averaged across a lifetime, 0.67
(95% CI, 0.51-0.89). Similar associations were observed for organ-confined
prostate cancer. Ejaculation frequency was not statistically significantly
associated with risk of advanced prostate cancer.
Conclusions Our results suggest that ejaculation frequency is not related to increased
risk of prostate cancer.