A vasectomy may increase the risk of aggressive prostate cancer, according to a recent study.

New research from scientists at Harvard University suggests that vasectomy is associated with a 10 percent increased risk of prostate cancer, and a 20 percent risk for advanced or lethal prostate cancer.

Vasectomy is a common form of contraception in the U.S., with about 15 percent of men having the procedure. Prostate cancer is the second-leading cause of cancer death among men in the United States, so identifying risk factors for lethal prostate cancer is important for public health.

The association remained even among men who received regular PSA screening, suggesting the increased risk of lethal cancer cannot be explained by diagnostic bias. It is the largest and most comprehensive study to date to look at the link between vasectomy and prostate cancer.

"This study follows our initial publication on vasectomy and prostate cancer in 1993, with 19 additional years of follow-up and tenfold greater number of cases. The results support the hypothesis that vasectomy is associated with an increased risk of advanced or lethal prostate cancer," Lorelei Mucci, co-author of the study and an associate professor of epidemiology at the Harvard School of Public Health, said in a statement.

For the study, researchers analyzed data from more than 49,000 men who were followed for up to 24 years from 1986 to 2010. During that time, 6,023 cases of prostate cancer were diagnosed, including 811 lethal cases. One in four of the men in this study reported having a vasectomy.

"The decision to opt for a vasectomy as a form of birth control is a highly personal one and a man should discuss the risks and benefits with his physician," Kathryn Wilson, co-author of the study and research associate in the Department of Epidemiology, said in a study.

The findings were recently published in the Journal of Clinical Oncology.