It has long been known that a first full-term pregnancy lowers the risk of breast cancer. Conversely, if a woman has an abortion that benefit is lost.
In early pregnancy, a 2,000 percent increased surge of estrogen stimulates rapid cell division resulting in a profusion of immature breast cells. Undifferentiated cells are unstable and more vulnerable to carcinogens.
By the third trimester these cells have matured into milk producing glands which become cancer resistant. Early abortion results in more vulnerable cells that can become cancerous than were present before pregnancy.
The World Health Organization and the U.S. National Toxicology Program recognize contraceptive steroids and hormone replacement therapy (HRT) as known carcinogens. Breast cancer rates dropped when women stopped HRT.
Oral contraceptives increase triple negative cancers by 240 percent and noninvasive breast cancers in premenopausal women by 400 percent since 1975.
Oral contraceptives contain the same drugs as HRT but in much higher doses. Seventy-five percent of our young women take them.
Undoubtedly breast cancer incidence would drop if women stopped ingesting these cancer inducing hormones
More information about risk factors and prevention can be found at Breast Cancer Prevention Institute and the Coalition on Abortion/Breast Cancer.