Thursday, August 02, 2007

Miscarriage Linked with Breast Cancer Risk

Women who experience a miscarriage in their first pregnancy appear have an increased risk of developing breast cancer after menopause, according to a new conducted in France.

Changes in the cells of the breast that follow a first full-term pregnancy are believed to protect women from breast cancer, Dr. Francoise Clavel-Chapelon, of Institut Gustave Roussy in Villejuif, and colleagues point out in the August 20th issue of the International Journal of Cancer. However, studies of the association between miscarriage and breast cancer risk have yielded conflicting results.

As part of a study begun in 1990, women between the ages of 40 to 65 years were asked about reproductive events and other demographic factors. The number of women who were diagnosed with breast cancer by 2000 was recorded.

Of more than 92,000 women, 22.1% had undergone induced abortions and 23.0% experienced miscarriages. Overall, induced abortion, but not miscarriage, was associated with a small reduction in risk of breast cancer.

Women who had given birth and who had also undergone two induced abortions had a 75% lower risk of breast cancer.

In contrast, the authors found an increased risk among women who had not given birth and who had had one or more miscarriages. The French team notes that the excess risk observed in women who had never given birth could be due to environmental factors, such as chemical exposure or radiation, or genetic factors.

There was a trend for decreased risk following miscarriage during the premenopausal period, whereas risk was significantly increased after menopause, regardless of pregnancy history. For those who had three or more miscarriages, the breast cancer risk was lower before menopause and higher afterwards. The protective effect of full-term pregnancies is apparently not acquired during the first trimester, the authors conclude, since the risk was not decreased after interrupted pregnancies.


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