While combined oral contraceptives, better known as The Pill, rank as Group I carcinogens according to a 2005 report released by the International Agency for Research on Cancer, an arm of the World Health Organization, doctors continue to routinely prescribe the pill for a variety of conditions, ranging from acne to birth control (American Cancer Society, 2008)....
Combined oral contraceptives are composed of estrogen and progesterone or progestin, a synthetic form of progesterone. Estrogen and progesterone are female sex hormones; estrogen thickens the lining of the uterus, and progesterone/progestin prepares the endometrium for implantation of the egg. (National Cancer Institute, 2006).
The reasoning behind a combination of estrogen and progesterone/progestin is that estrogen given on its own increases the risk of uterine cancer. Taking a combination of the 2 confers protection from uterine cancer but increases breast cancer risk.
In short, the science behind the increased breast cancer risk stems from 2 primary mechanisms. In both instances, progesterone/progestin becomes a double-edged sword, as it confers protection from increased uterine cancer risk but "gives permission" for estrogen to negatively affect breast DNA.
First, the combination of estrogen plus progesterone/progestin functions as a genotoxin, meaning it directly damages DNA in the breast. Several estrogen metabolites, or breakdown products, including 4-hydroxy-catechol-estrogen quinine, have been proven to function in this manner (Lanfranchi, 2007).
Second, estrogen functions as a mitogen, or cancer promoter, and estrogen promotes cancer in 2 ways. As seen in the graph, it stimulates an explosion of rapid proliferation of cells in breast lobules, causing a greater likelihood of mutations with the increased rate of division.
Additionally, estrogen promotes speedier development of any already-cancerous cells in the breast (Lanfranchi, 2007).
Why doesn't the American public know about the increased risk? Why is the teenage girl on the pill for acne unaware of the health risks involved? Women deserve better.