A relationship between vasectomy and prostate cancer
risk was initially suggested in
1993 with a relative risk of
1.6 based on two large cohort studies (Giovannucci et al, 1993a, 1993b  ). Risk increased with time, so that men who underwent vasectomy at an early age had a higher risk. A recent meta-analysis reported a pooled risk of 1.37, with a linear trend suggesting a 10% increase for each additional 10 years since vasectomy ( Dennis et al, 2002a ).