Breast cancer was found to be more common in women who used birth control pills, had a child after the age of 27, breastfed their babies less, had an abortion and began menstruating at an early age, in new research conducted in India.
Women who began their menstrual cycle before the age of 16 were 2.76 times more likely to develop breast cancer. The risk increased 9.5 times for women who used birth control pills, 6.26 times for an abortion, 14.9 times for breastfeeding less than 13 months, 3.29 times for having a child after the age of 27, and 2.68 times for beginning menopause after age 49, according to the research conducted by A.S. Bhadoria, U. Kapil, N. Sareen and P. Singh, of the Department of Gastroenterology and Human Nutrition Unit, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
The article, "Reproductive factors and breast cancer: A case-control study in tertiary care hospital of North India," was published in the December issue of Indian Journal of Cancer.
The researchers examined 320 Indian women with verified cases of breast cancer and compared them to a control group of 320 women without breast cancer. The control group was matched with the breast cancer cases based upon similar ages and socioeconomic status.
The research also found that women who married after age 20 were 2.69 times more likely, and women who had their first child after age 21 were twice as likely, to develop breast cancer. Those differences, though, were not statistically significant.
One of the strongest predictors of breast cancer, the researchers note, is family history. Among the study's breast cancer cases, 21.3 percent reported that family members also had the disease. In the control group, there were no reports of breast cancer among relatives.
On the link between abortion and breast cancer, the report says that other studies have been inconclusive. Some studies have found a positive correlation, others have found a negative correlation, and a few have found no correlation. Their study is also inconclusive, the researchers wrote, because they did not distinguish between an induced abortion and a miscarriage.