The Coalition on Abortion/Breast Cancer notes a study of 1,028 women ages 20-44 in the April 15, 2012 issue of Cancer Research found that recent users of depo provera (DMPA) for 12 months or more had a statistically significant 2.2-fold increased risk of developing invasive breast cancer.  The authors, Christopher Li and his team (including Janet Daling) at the Fred Hutchinson Cancer Research Center called it the "first large scale U.S. study" examining the link between DMPA and breast cancer. They concluded it's the fifth study "conducted over a diverse group of countries that have observed that recent DMPA use is associated with a 1.5- to 2.3-fold increased risk of breast cancer." 
Li's team said the 2003 Women's Health Initiative study of hormone replacement therapy (HRT) "strongly suggest" that agents containing progestin, "medroxyprogesterone acetate (MPA), in particular, increase a woman's risk of breast cancer." MPA combined with estrogen raised risk by 24%, while estrogen only replacement therapy "had a nonstatistically significant reduced risk." 
Like cancer-causing oral contraceptives (the pill) and combined (estrogen + progestin) HRT, the DMPA-breast cancer link supports an abortion-breast cancer link. Estrogen in the presence of progesterone (i.e. progestin) stimulates the growth of cancer-susceptible Type 1 and 2 breast lobules.
"In the case of DMPA or any other progestin-only pill, the estrogen component is provided by the woman's own ovarian estrogen," reported Joel Brind, professor of human biology and endocrinology at Baruch College, City University of New York.
Karen Malec, president of the Coalition on Abortion/Breast Cancer, added:
"In implementing Obamacare, the federal government will require employers to purchase insurance that provides women free abortifacients, contraceptives and sterilizations, including DMPA. Why offer free drugs that damage women's health, but not free life-saving drugs? That's the perfect definition of a war on women!
"Cancer groups should have implemented a nationwide awareness campaign about the DMPA-breast cancer link, but it's no surprise they didn't. They've lied to women about the risks of abortion, oral contraceptives and combined hormone replacement therapy for decades. They still haven't reported that two studies since 2009 strongly linked oral contraceptive use with the deadly triple-negative breast cancer." [4,5]
The Coalition on Abortion/Breast Cancer is an international women's organization founded to protect the health and save the lives of women by educating and providing information on abortion as a risk factor for breast cancer.
1. Li C, Beaber E, Tang M, Porter P, Daling J, Malone K. Effect of depo-medroxyprogesterone acetate on breast cancer risk among women 20 to 44 years of age. Cancer Research 2012;72(8):2028-2035.
2. Ibid, p. 2034.
3. Ibid, p. 2028.
4. Dolle J, Daling J, White E, Brinton L, Doody D, et al. Risk factors for triple-negative breast cancer in women under the age of 45 years. Cancer Epidemiol Biomarkers Prev 2009;18(4)1157-1166. Available at: <http://www.abortionbreastcancer.com/download/Abortion_Breast_Cancer_Epid_Bio_Prev_2009.pdf>.
5. Ma H, Wang Y, Sullivan-Halley J, Weiss L, Marchbanks PA, Spirtas R, Ursin G, Burkman RT, Simon MS, Malone KE, Strom BL, McDonald JA, Press MF, Bernstein L. Use of four biomarkers to evaluate the risk of breast cancer subtypes in the Women's Contraceptive and Reproductive Experiences Study. Cancer Research 2010;70(2):575-587. Available at: <http://cancerres.aacrjournals.org/content/70/2/575.long>.