Ejaculation frequency, a measure of sexual activity, is not associated with a higher risk for prostate cancer, according to a study in the April 7 issue of The Journal of the American Medical Association (JAMA). However, a high ejaculation frequency may be linked to a decreased risk of prostate cancer.

Sexual activity has been hypothesized to play a role in the development of prostate cancer, according to background information in the article. Given that sexual activity is common and that prostate cancer risk is high, any association between these factors would have clinical and public health relevance.

Michael F. Leitzmann, M.D., of the National Cancer Institute, Bethesda, Md., and colleagues examined the association between ejaculation frequency (which includes sexual intercourse, nocturnal emission, and masturbation) and risk of prostate cancer. The study used follow-up data from the Health Professionals Follow-up Study (February 1, 1992, through January 31, 2000) of 29,342 men in the U.S., 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).

Among the participants, there were 1,449 new cases of total prostate cancer, 953 organ-confined cases, and 147 advanced cases of prostate cancer.

"In this prospective cohort study among predominantly white men, higher ejaculation frequency was not related to increased risk of prostate cancer. Our results suggest that high ejaculation frequency possibly may be associated with a lower risk of total and organ-confined prostate cancer. These associations were not explained by potential risk factors for prostate cancer, such as age, family history of prostate cancer, history of syphilis or gonorrhea, smoking, and diet," the authors write.

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(JAMA. 2004;291:1578-1586. Available post-embargo at JAMA.com)

Editor's Note: This work was supported by research grants to co-author Dr. Walter Willett from the National Institutes of Health and by a Cancer Epidemiology Training grant to Dr. Leitzmann from the National Cancer Institute.