Vasectomy and prostate cancer risk in China
Hsing, A.W.; Wang, R.T.; Gu, F.L.; Lee, M.; Wang, T.; Leng, T.J.; Spitz, M.; Blot, W.J.
Cancer Epidemiology Biomarkers and Prevention a Publication of the American Association for Cancer Research Cosponsored by the American Society of Preventive Oncology 3(4): 285-288
1994
ISSN/ISBN: 1055-9965 PMID: 8061575 Document Number: 285999
This paper reports the findings of a hospital-based case-control study that was conducted at major teaching hospitals in 12 cities in China. China reports the lowest incidence in prostate cancer of over 100 registries reporting cancer incidence. This investigation evaluated the relationship between vasectomy and prostate cancer and attempted to identify any etiological factor. A total of 138 study patients (index cases) were identified. Controls used in this study included a cancer control and a noncancer control from the same hospital, and 2 neighborhood controls. Chances of having prostate cancer were statistically determined by logistic regression analysis with age group adjustments made. The analysis reviewed 138 cases and 638 controls. Results indicate that, regardless of the variable control used for comparison, an increased risk of prostate cancer was associated with having had a vasectomy. Statistical odds ratio was 2.0 for hospital cancer controls (95% confidence interval [CI]; 0.7-6.1); 3.3 for hospital noncancer controls (95% CI; 1.0-11.3); and 6.7 for neighborhood controls (95% CI; 2.1-21.6). The authors conclude that, as reported for men in Western countries, Chinese men who have had a vasectomy are at significantly increased risk for developing prostate cancer compared to men who never have had a vasectomy. They report a near 2-fold increase in risk (vasectomy vs. non-vasectomy) in developing the disease. Conclusions about cause and effect are premature, but these findings warrant further investigation of several issues. These include: changes in the endocrine system due to vasectomy; systematic and local immunity changes after vasectomy; and other possible biochemical factors that enhance/inhibit cancer growth in the prostate gland.