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 [109] [110]). 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 ).