Breast cancer is the most widely spread cancer all over the world. More than 30,000 women in the United States are expected to die from breast cancer this year. Researchers now believe small family size and reduced breastfeeding may be an important factor fueling this ever-growing epidemic.
Researchers from England evaluated 40 prior studies from 25 countries that included information on breastfeeding and childbearing patterns. Together, the studies involved more than 30,000 women with invasive breast cancer and nearly 80,000 women without breast cancer. Researchers say the goal of the study was to determine if breastfeeding protects against breast cancer in the same way childbearing is known to do.
Results of the study show an overwhelming association between smaller family size and reduced breastfeeding and an increased incidence of breast cancer. On average, women with breast cancer had fewer children than those who did not have breast cancer. In addition, mothers who did not breastfeed or who breastfed for shorter durations (around 10 months compared to 15 months) were at a significantly higher risk of developing breast cancer than those who did breastfeed longer.
Researchers report the overall risk of breast cancer decreased by 4.3 percent for every year a woman breastfed in her lifetime. Additionally, there was a 7-percent decrease for every birth regardless of whether the mother ever breastfed.
Valerie Beral, one of the researchers in the study, says, "The results of this study are a major step forward in our understanding of why breast cancer is so common in developed countries." Researchers say the incidence of breast cancer in developed countries may be reduced by more than half if women still had as many children and breastfed them for as long as they had in the past.
However, authors of the study acknowledge it is unrealistic to expect women of today to return to the childbearing and breastfeeding patterns that existed a century or so ago. Yet they do point out "...Even if women were to breastfeed each of their children for an additional six months, this could prevent about 5 percent of breast cancers each year."