In an article in the journal European Urology, Jennifer R. Rider, assistant professor of epidemiology, and colleagues found that an ejaculation frequency of 21 or more times per month at ages 20–29 years or 40–49 years is associated with a significant, 19 percent and 22 percent decreased risk of a PCa diagnosis, respectively, compared with a frequency of 4 to 7 times per month in adjusted analyses. Similar results were found when the analysis was restricted to men who had undergone prostate specific antigen (PSA) screening, which is strongly related to prostate cancer detection.
“More frequent ejaculation in the absence of risky sexual behaviors could represent an important means of reducing the profound medical costs and physical and psychological side effects of unnecessary diagnosis and treatment of low-risk tumors, even though it appears to be less strongly associated with aggressive disease,” the researchers concluded in their online report.
Results also showed that ejaculation frequency at ages 20–29 or 40–49 was significantly associated with approximately 25 percent reductions in intermediate-risk PCa when comparing men who reported 13 or more ejaculations per month with those who had 4 to 7 ejaculations per month.
Ejaculation frequency was not significantly associated with a diagnosis of high-risk PCa or regional/distant metastases, according to the researchers.
“This large prospective study provides the strongest evidence to date of a beneficial role of ejaculation in prevention of PCa, a disease for which relatively little is understood about etiology generally, and knowledge of modifiable risk factors is particularly scant.”
Rider and her colleagues conducted a prospective cohort study of 31,925 men who participated in the Health Professionals Follow-up Study (HPFS). All answered questions about ejaculation frequency on a 1992 questionnaire and were followed to 2010. During 480,831 person-years of follow-up, 3,839 men were diagnosed with PCa—1,585 with localized low-risk disease, 1,493 with localized intermediate-risk disease, 604 with localized high-risk PCa, and 157 with evidence of regional or distant metastases at diagnosis.
The new findings build on an initial study of the HPFS cohort published in 2004, in which researchers found a statistically significant inverse relationship between monthly ejaculation frequency and PCa risk, based on eight years of follow-up and less than half the number of prostate cancer cases. That study, published in the Journal of the American Medical Association, found that men reporting 21 or more ejaculations per month had a 50 percent lower risk of PCa than those reporting 4 to 7 ejaculations per month, but the association was limited to ejaculation frequency in the year before the questionnaire and not ages 20–29 or 40–49. Unlike the present study, the initial study was not able to evaluate clinically relevant disease subgroups or evaluate the potential impact of PSA screening on the results.
Rider joined the faculty at SPH in October. Co-authors on the study came from the Harvard T.H. Chan School of Public Health.