|
Women who miscarry during pregnancy or even undergo abortion procedures are not at an increased risk of breast cancer, a new study says. Earlier studies had hinted premenopausal women were at increased risk of breast cancer if they had induced or spontaneous abortion.
During pregnancy there is considerable breast cell differentiation, which prepares them to perform specialized roles after delivery. Since a long time, researchers have theorized that either induced or spontaneous abortion may trigger breast cancer development because these cells remain differentiated and may proliferate to cause cancer later on.
It is noted women aged under 35 who carry a pregnancy to full term are at a reduced risk for breast cancer. Earlier retrospective studies have highlighted abortion and miscarriages are certain risk factors in breast cancer development.
But a study by researchers at the Cancer Research UK Epidemiology Unit, University of Oxford in the UK found no such link last year. The study, which followed 267,361 women recruited into the European Prospective Investigation into Cancer and nutrition, was published in the October 2006 issue of the International Journal of Cancer.
The study was conducted between 1992 and 2000 during which 4,805 women were diagnosed with breast cancer. Of them 1,657 reported having had abortion, but researchers did not find significant co-relation between abortion and breast cancer risk.
The present study by researchers at the Brigham and Women’s Hospital, Harvard Medical School and the Harvard School of Public Health appears to reinforce the findings of the European study. Data from the Nurses' Health Study II (NHS II) in 1993 was used to find if any link existed between breast cancer and abortions.
The study had 105,716 women ages 29 and 46 years. Around 93 percent women were premenopausal and all were cancer-free at the beginning of the study. Researchers collected data from a questionnaire in which women revealed their abortion history is any.
Researchers report in The Archives of Internal Medicine that 16,118 in the study had one or more induced abortions, while 21,753 had miscarried. Among the 105,716 participants researchers said there were 1,458 newly diagnosed cases of breast cancer.
Breast cancer incidence was unrelated to spontaneous or induced abortions and did not vary in women who had abortions and those who never had them.
But researchers admitted women under 35 had reduced risk of breast cancer if they carried a pregnancy to full term. Therefore it is surmised that a pregnant woman who has either spontaneous or induced abortion has an increased for breast cancer as opposed to if she does carry the pregnancy to full term.
Karin Michels, the lead author of the study and an associate professor of epidemiology at Harvard said there was no plausible link between breast cancer and abortion. “There are still some states that require women to be informed about the risk of breast cancer if they get an abortion,” she told the New York Times. “I think that may not be justified based on the current evidence.”
However researchers were unable to explain the link between a full term pregnancy and reduced risk of breast cancer. "We observed associations in two subgroups, an association between induced abortion and progesterone receptor-negative breast cancer (cancer that does not respond to the hormone progesterone) and an inverse association between spontaneous abortion before the age of 20 years and breast cancer incidence," they wrote.
Breast cancer is the most frequently diagnosed non-skin cancer in American women, according to the National Cancer Institute. Some of the identified risk factors for breast cancer include personal history of breast abnormalities, current age, age at first menstrual period, age at first live birth, breast cancer history of close relatives, whether a woman has had a breast biopsy, obesity, physical inactivity, and race.
Use of hormone therapy and breast density also play a role in increasing risk of breast cancer. The National Cancer Institute says there is no evidence linking breast cancer to abortion although some studies have documented such a risk.
But Joel Brind, a professor of biology and endocrinology at Baruch College in Manhattan believes "having an abortion increases the risk about 30 percent over not having gotten pregnant in the first place"
The current study says that some women are scared of the stigma attached to abortion and do not admit to having undergone any such procedure. It is only when they are diagnosed with breast cancer do they look for an association. Dr Michels said women who had undergone abortions had them 10 years before the breast cancer diagnosis.
Breast cancer is caused by multiple factors, but based on available data from large studies it does not appear to be linked to abortion.
 Add as favourites (41)
Powered by AkoComment Tweaked Special Edition v.1.4.4 |
Health 
