I recall reading some article with a related point of view - talking about cervical cancer. The authors had the same hypothesis, hormones elevated the risk.
They then did a study involving associated data, like number of miscarriages, age of onset of puberty, effect of good nutrition. They looked at the records of an African tribe that had the custom of a separate housing for women during menstruation. (wtf?) Basically, they suggested that in modern western society women experienced about twice as many periods as historically. Good nutrition has brought on much earlier periods and later menopause; malnutrition can also stop menstruation. Before birth control, women had many more children (many of whom, sadly, died) and even more miscarriages, thus missing many more periods. They guesstimated women today experience about twice as many periods as historically.
So part of the issue may be a better lifestyle leading to higher risk. The same might be said of prostate cancer. Men live much longer nowadays, giving them a chance to encounter it. As the doctor on "Frankie and Grace* said about slow prostate cancer, “The good news is something else will probably kill you first.”