Circumcision before a male's first sexual intercourse might reduce his risk of developing prostate cancer by 15 percent, according to a new study published online March 12 in Cancer.

Researchers surveyed 3,399 men, and among them 1,754 were diagnosed with prostate cancer and 1,645 were not.  Researchers found that men who had been circumcised before their first sexual experience intercourse were 15 percent less likely to develop prostate cancer compared to uncircumcised men. 

Men who were circumcised were 18 percent less likely to develop more aggressive forms of prostate cancer and 12 percent less likely to develop less aggressive prostate cancer. 

Researchers are unsure of the exact cause and effect of circumcision and lower cancer risk, but they pointed out that sexually transmitted infections increase the risk of prostate cancer because chronic inflammation creates a “hospitable environment for cancer cells,” they said in a statement released on Monday.

Previous studies have linked male circumcision to a reduced risk of HIV infection and other sexually transmitted disease.  However the new finding does not mean that prostate cancer is definitely linked to viral infection, like penile and anal cancers have been linked to the human papillomavirus (HPV), which can be spread during various sexual activities. 

The researchers said that the infection may lead to chronic inflammation in the body which would thus create a more nurturing environment for cancer cells.

Researchers said that circumcision may reduce the risk of STIs, and therefore prostate cancer, because it toughens the inner foreskin and removes of the moist space under the foreskin that may help bacteria survive.

Male circumcision is the removal of the foreskin, which covers the tip of the penis.  The benefits to circumcision are that it may risk of urinary tract infections, penile cancer and sexually transmitted diseases, and the risks include pain and risk of bleeding or infection. 

"These data are in line with an infectious/inflammatory pathway which may be involved in the risk of prostate cancer in some men," said lead author Dr. Jonathan Wright of the University of Washington School of Medicine said in a statement. "Although observational only, these data suggest a biologically plausible mechanism through which circumcision may decrease the risk of prostate cancer. Future research of this relationship is warranted," he added.

Researchers noted the findings need to be studied further, and that established cancer risk factors like older age and family history have already been established and should help patients and physicians best determine about prostate-specific antigen (PSA) blood test screening.  In 2011, the U.S. Preventive Services Task Force recommended that against PSA screening for healthy men.