One is too much sex. You can actually get cervical carcinoma from that. Another is not enough sex. So nuns have a higher incidence of ovarian cancer. The wrong kind of sex.
Aids patients have an increased incidence of rectal carcinoma.
There are three different ideologies you have to deal with. Each one of these plays a role. Well, have safe sex in moderation. The next best thing is screening for cancer. Early detection has the best survival.