I'm no medical expert...
but I would think, based on my understanding, that the benefits of
oral contraceptives as a preventative of ovarian cancer would be about the same as those of having children and breastfeeding them over a natural period of time. And little toxic pills don't call you on your birthday or fill up your living room on Christmas morning. (And I mean real pharmacological pills. Some of my children have been known to act like toxic little pills at times, but that is definitely not what I'm getting at here.)