So here comes a medical study with plenty of power–40,000 subjects so it has statistical significance. HOWEVER!!!!
Here’s the problem. The relative risk is miniscule, at 1.10 for prostate cancer rate and 1.19 for prostate cancer deaths.
So if the study was repeated there might be no effect. They said they adjusted for confounders? However you can’t adjust for randomness. They admit the absolute risk is miniscule, but they don’t admit the limits of an ecological observational epidemiological study. This ain’t no Randomized Controlled Trial.
People who get upset about cancer clusters suffer the same illiteracy, or is it innumeracy?
Vasectomy Linked to Prostate Cancer in 24-Year Study
RESEARCH · July 07, 2014
Analysis of 40,405 men from the Health Professionals Follow-Up Study found an increased risk for overall (HR, 1.10) and lethal (HR, 1.19) prostate cancer in men who underwent vasectomy, despite controlling for confounding factors. The overall risk for death from prostate cancer in the entire population was 1.6% over a 24-year follow-up period.
Although statistically significant, the increased association of prostate cancer and risk for death with vasectomy translates into a small absolute risk, and the biologic rationale behind the finding is unclear.
– Richard Bambury, MD
Conflicting reports remain regarding the association between vasectomy, a common form of male contraception in the United States, and prostate cancer risk. We examined prospectively this association with extended follow-up and an emphasis on advanced and lethal disease.
PATIENTS AND METHODS
Among 49,405 US men in the Health Professionals Follow-Up Study, age 40 to 75 years at baseline in 1986, 6,023 patients with prostate cancer were diagnosed during the follow-up to 2010, including 811 lethal cases. In total, 12,321 men (25%) had vasectomies. We used Cox proportional hazards models to estimate the relative risk (RR) and 95% CIs of total, advanced, high-grade, and lethal disease, with adjustment for a variety of possible confounders.
Vasectomy was associated with a small increased risk of prostate cancer overall (RR, 1.10; 95% CI, 1.04 to 1.17). Risk was elevated for high-grade (Gleason score 8 to 10; RR, 1.22; 95% CI, 1.03 to 1.45) and lethal disease (death or distant metastasis; RR, 1.19; 95% CI, 1.00 to 1.43). Among a subcohort of men receiving regular prostate-specific antigen screening, the association with lethal cancer was stronger (RR, 1.56; 95% CI, 1.03 to 2.36). Vasectomy was not associated with the risk of low-grade or localized disease. Additional analyses suggested that the associations were not driven by differences in sex hormone levels, sexually transmitted infections, or cancer treatment.
Our data support the hypothesis that vasectomy is associated with a modest increased incidence of lethal prostate cancer. The results do not appear to be due to detection bias, and confounding by infections or cancer treatment is unlikely.
Journal of Clinical Oncology
Vasectomy and Risk of Aggressive Prostate Cancer: A 24-Year Follow-Up Study
J. Clin. Oncol 2014 Jul 07;[EPub Ahead of Print], MM Siddiqui, KM Wilson, MM Epstein, JR Rider, NE Martin, MJ Stampfer, EL Giovannucci, LA Mucci
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.