Breast-feeding Does Not Up Later Cancer Risk

NEW YORK (Reuters Health) - Contrary to an old notion, adults who were breast-fed as infants are not at increased risk for cancer, researchers report.

In the 1930s, researchers hypothesized that by transmitting cancer-causing viruses, breast-feeding could increase the risk of malignancy. Since then, a number of studies have looked at this issue, but have failed to yield conclusive results.

In the present study, in the Journal of the National Cancer Institute, Dr. Richard Martin at from the University of Bristol in the UK, and colleagues, investigated the possible association by analyzing data from 4379 subjects who were evaluated in childhood in the late 1930s and then followed up through 2003 to assess cancer occurrence.

There was little or no evidence from this study that breast-feeding influenced the risk of cancer, in general, or the risk of a particular type.

The researchers also analyzed pooled data from 14 studies that looked at the effect of infant feeding on cancer risk, and this too showed that breast-feeding did not have an effect on the overall risk of breast cancer in adulthood.

However, breast-feeding was associated with a 12 percent decreased risk of women developing breast cancer before menopause.

SOURCE: Journal of the National Cancer Institute, October 5, 2005.