The Coalition on Abortion/Breast Cancer notes that a Chinese study consisting of 1,351 subjects published in the Asian Pacific Journal of Cancer Prevention in February, 2012 reported a very statistically significant increased risk of breast cancer for women with previous induced abortions (IAs) in comparison with women without previous IAs. [1]Researchers led by Ai-Ren Jiang reported a statistically significant 1.52-fold elevation in risk for women with IAs and a "significant dose-response relationship between (the risk) for breast cancer and number of (IAs)," meaning that risk climbed with number of IAs.
For premenopausal women with IAs, the numbers were relatively small, and the observed 16% risk elevation was not statistically significant. However, for those with three or more IAs, the risk climbed to a statistically significant 1.55-fold elevation.
By contrast, postmenopausal women with IAs experienced a statistically significant 1.82-fold elevation in risk, compared to those with no IAs. Risk climbed with number of IAs from a statistically significant 1.79-fold increased risk for one IA and a statistically significant 1.85-fold elevation for two IAs, to a non-statistically significant 2.14-fold elevated risk for three or more IAs.
Professor Joel Brind (Baruch College, City University of New York) advised the Coalition on Abortion/Breast Cancer that earlier Chinese studies [3,4] underestimated the breast cancer risk of IAs. A one-child-per-couple policy is in force, and most women have abortions after first full term pregnancy. (First full-term pregnancy reduces risk by maturing 85% of the mother's cancer-susceptible breast lobules into permanently cancer-resistant lobules.) He said it:
"tends to suppress the relative risk values, which makes the Jiang numbers all the more credible - underestimates if anything. Also, a place like China is good to measure the dose effect of abortion, and the statistics are strong enough to show a highly significant trend, which strengthens a causal inference."
A Chinese study in 1995 by L. Bu and colleagues, including Janet Daling of the Fred Hutchinson Cancer Research Center, reported a statistically significant 4.5-fold elevated risk among women with IAs who developed breast cancer at or before age 35, compared to older women (who experienced a statistically significant 2.5-fold elevated risk). [2]
Four of seven Chinese studies report statistically significant risk increases for women with IAs. Fifty-three of sixty-nine epidemiological studies dating from 1957 report risk elevations for women with previous IAs. Biological and experimental research supports an abortion-breast cancer link. [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.
References:
1. Jiang AR, Gao CM, Ding JH, Li SP, Liu YT, Cao HX, Wu JZ, Tang JH, Qian Y, Tajima K. Abortions and breast cancer risk in premenopausal and postmenopausal women in Jiangsu Province of China. Asian Pacific J Cancer Prev 2012;13:33-35. Available at: <http://www.apjcpcontrol.org/page/popup_paper_file_view.php?pno=MzMtMzUgMTIuMiZrY29kZT0yNzAxJmZubz0w&pgubun=i>.
2. Bu L, Voigt L, Yu Z, Malone K, Daling J. Risk of breast cancer associated with induced abortion in a population at low risk of breast cancer. Am J Epidemiol 1995;141:S85. (abstract).
3. Ye Z, Gao DL, Qin Q, Ray RM, Thomas DB. Breast cancer in relation to induced abortions in a cohort of Chinese women. Br J Cancer 2002;87:977-981.
4. Sanderson M, Shu X-O, Jin F, Dai Q, Wen W, Hua Y, Gao Y-T, Zheng W. Abortion history and breast cancer risk: results from the Shanghai breast cancer study. Int J Cancer 2001;92:899-905.
5. For a list of 68 of those epidemiological studies, see: <http://bcpinstitute.org/epidemiology_studies_bcpi.htm>. One study excluded from this list was: Carroll, P. The breast cancer epidemic: modeling and forecasts based on abortion and other risk factors." J Am Phys Surg Vol. 12, No. 3 (Fall 2007) 72-78. Available at: <http://www.jpands.org/vol12no3/carroll.pdf>.