In an article by Wright et al in Cancer (2012) circumcision before first sexual intercourse reduced lifetime risk of prostate cancer by a relative risk of 15%. This is an interesting observation with many possible confounders which should stimulate further research rather than change practice.
The investigators analyzed data from 1754 patients and 1645 control participants collected during 2 population-based, case-control studies of prostate cancer. Data included self-reported circumcision status, age at circumcision, age at first sexual intercourse, and history of STIs or prostatitis. Of the men who reported circumcision, 91% underwent the procedure shortly after birth. Circumcision was performed after the date of first intercourse in 3.9% of patients with prostate cancer (case patients) and in 2.5% of control participants. Reduction in prostate cancer risk associated with circumcision before first sexual intercourse was apparent for case patients with less aggressive features of prostate cancer (OR, 0.88; 95% CI, 0.74 – 1.04) as well as for patients with more aggressive features (OR, 0.82; 95% CI, 0.66 – 1.00). The effect of circumcision on the risk for prostate cancer was not affected by age, STI status, study 1 vs study 2, history of prostatitis, family history of prostate cancer, education, or income level. Circumcision after first sexual intercourse was not associated with the risk for prostate cancer. They suggest that circumcision might reduce the development of prostate cancer by decreasing prostatic exposure to infectious agents and the associated inflammatory changes that may enhance carcinogenesis. They refer to data showing reduced HIV and HPV risk in circumcised men.