NEW YORK, Jul 29 (Reuters Health) -- Pregnancy during adolescence probably does not increase the risk of subsequent breast cancer, but breastfeeding during adolescence may be protective against the disease, according to data from the Carolina Breast Cancer Study. African-American adolescents who use oral contraceptives may also be at increased risk of breast cancer.
Dr. Pamela M. Marcus, of the National Cancer Institute in Bethesda, Maryland, and a multicenter team collected data via personal interviews with a total of 862 case patients and 790 'control' subjects. Their study results are published in the August issue of the American Journal of Public Health, the journal of the American Public Health Association.
Using a statistical model, the researchers determined that full-term pregnancy, defined as gestation of 7 months or more, before age 20 did not increase or decrease the risk of breast cancer relative to women with a first full-term pregnancy between the ages of 20 and 29.
However, mothers who breast-fed before age 20 had a substantially reduced risk of developing breast cancer relative to premenopausal women who did not breastfeed their children. The research team cautions, however, that "this result was based on small numbers of women reporting lactation during their teen years."
Marcus said in an interview with Reuters Health that she and her associates observed "no elevation in breast cancer risk for women who had induced abortions as teens, as compared with women who had other pregnancy outcomes at those ages." This finding suggests, she said, "that pregnant teens who are considering induced abortion need not be concerned about its effect on subsequent breast cancer risk."
The investigators calculated an increased risk of breast cancer among African-American women who used oral contraceptives before the age of 18, relative to African-American women who had never used oral contraceptives. "Among white women, no such relationship was observed,"they write.
"We are unsure why the effect of teen oral contraceptive use on subsequent breast cancer risk would be different for white and African-American women," Marcus told Reuters Health. "Such a finding may be due to other breast cancer risk factors that are correlated with oral contraceptive use in African-American women." "Nevertheless," she added, "this possible increase in risk warrants further study."
SOURCE: American Journal of Public Health 1999;89:1244-1247.
Ann's NOTE: For much more on pregnancy, fertility and abortion issues, see Relevant Studies, then Pregnancy section.
Arch Dis Child, 2007; 92(9): 750-3. August 2007
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