Breast Cancer and Breast-Feeding

A woman who lives in the United States has a 1 in 8 chance of developing breast cancer if she lives to the age of 90. It is estimated that 203,500 cases of breast cancer were diagnosed in 2002 and 39,600 deaths attributed to it. To decrease deaths from breast cancer efforts have focused on earlier detection and better treatments. Prevention of breast cancer is another area to focus on. In general we don’t know how to prevent breast cancer but we do know what factors increase (risk factors) and decrease (protective factor) the chances of getting breast cancer.

Breast milk is the ideal food for babies. It contains all the nutrients needed for the first months of a baby’s life. Breast fed babies get fewer ear infections, are less likely to develop asthma and other chronic illnesses. Some studies have shown a higher IQ amongst breast fed babies. Breast milk doesn’t cost anything (formula costs $100-300 a month) and is always ready to give to a hungry baby.

No, my computer hasn’t mixed up the introductions to 2 different articles. The decrease in breast-feeding amongst women in developed countries has a direct correlation to the increase in breast cancers in these countries according to a study published in the Lancet, a British medical journal similar to The New England Journal of Medicine.

Childbearing can protect against developing breast cancer but it has been difficult to separate out the separate effect breastfeeding has on breast cancer risk. Obviously duration of breastfeeding is inseparable from many aspects of childbearing including number of children and age of childbearing. The Lancet study combined data from 30 different countries, studying 50,302 women with breast cancer and 96,973 women without the disease. The investigators found that the risk of breast cancer decreased by 4.3% for each year a woman breastfeeds in addition to a decrease of 7% for each birth. The decreased risk was consistent amongst different ethnic groups, developed and developing countries, number of births, age of first birth and other variables thought to affect the risk of breast cancer such as family history, height, weight, alcohol and tobacco use and age of the first menstrual period. It is of interest that the United States had the lowest number of women who had ever breast fed (around 50%), whereas in Japan, Scandinavia and developing countries more than 90% of women had ever breast-fed.

The authors conclude that if women had larger families and increased duration of breast feeding, patterns that were common until the last century, the incidence of breast cancer would be reduced by more than half (from 6.7 to 2.3 cases per 100 women) by age 70. It is inconceivable that women will increase their family sizes to prevent breast cancer, however longer duration of breast-feeding could reduce the incidence of breast cancer by 42%. The authors maintain that if women in developed countries continue to have an average of 2-3 children but breast feed for 6 months longer than they do now 25,000 breast cancers would be prevented each year.

There are all sorts of advantages to mother and child from breastfeeding. Women who breastfeed for more than three months also have the least amount of residual weight gain from pregnancy thus decreasing the chance of obesity later in life, obesity in itself being associated with a higher risk for breast cancer. All women should consider using their breasts for what they were intended…feeding their children.