How can lack of circumsision affect the risk of penile cancer? and what is the reason for this? is it because of the collection of smegma?

Circumcision&cancer: Unfortunately the best evidence we have is that there is conflicting evidence of circumcision preventing penile cancer - especially when you factor in smegma and phimosis. Uncircumcised males may be at risk for sexually transmitted diseases and genital warts as the foreskin may trap things. Good genital hygiene is important to clean the entire penis. Hope this helps