Prostate cancer is the second most common cancer in men worldwide, and the most frequently diagnosed cancer among men in the United Kingdom (UK). Currently, there are few identified risk factors for prostate cancer (age, black race, family history of prostate cancer, and genetics). This study seeks to examine if reproductive factors alter risks for prostate cancer diagnosis, survival, and death. Reproductive factors to be assessed include vasectomy (a medical procedure for male sterilization that prevents the release of sperm when a man ejaculates), infertility (a medical condition in a man that lowers the chances of his female partner getting pregnant), sexually-transmitted diseases (infections transmitted through sexual contact, caused by bacteria, viruses, or parasites), erectile dysfunction (a medical condition in which men are unable to maintain an erection for sexual intercourse), prostatitis (a medical condition resulting in swelling of the prostate), and varicocele of the scrotum or testicle (a medical condition where veins are enlarged within the loose bag of skin that holds men’s testicles).
We propose to investigate whether reproductive factors are associated with risks of incident prostate cancer, death from prostate cancer, and survival among prostate cancer cases. This nested case-control study in the Clinical Practice Research Datalink (CPRD) will be comprised of prostate cancer cases with incidence-density matched controls based on a 4:1 ratio using the variables age, general practice, and length of time in CPRD.
In the main analysis we will assess specified reproductive factors— vasectomy, infertility, sexually-transmitted diseases (STDs), erectile dysfunction, prostatitis, and varicocele—in relation to risks of incident prostate cancer, prostate cancer death, and prostate cancer survival using all available data from CPRD GOLD, HES Inpatient and Outpatient, NCDR Cancer Registry, and ONS Mortality data to define exposures and outcomes. Sensitivity analyses will test whether any result is affected by the time-limits of the database linkages. For prostate cancer incidence and death, we will use conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs). For the case-only prostate cancer survival analyses, we will use Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% CIs.
HES Admitted Patient Care;HES Outpatient;NCRAS Cancer Registration Data;ONS Death Registration Data;Patient Level Townsend Score