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Taken from here - https://news.bio-medicine.org/medic...ibution-to-incidence-of-breast-cancer-7504-1/
Reduced breastfeeding in western countries makes major contribution to incidence of breast cancer
Small family size and short-duration or no breastfeeding in Western populations substantially increases the risk of breast cancer, conclude authors of a study in this week's issue of THE LANCET. An estimated 25,000 breast cancers would be prevented in Western populations every year if women continued to have the same number of children but breastfed each child for six months longer.
Childbearing is known to protect against breast cancer; however it has been unclear whether breastfeeding contributes to this protective effect. In an international collaborative study, Valerie Beral from the Cancer Research UK Epidemiology Unit, Oxford, UK, and colleagues pooled and analysed data from 47 epidemiological studies in 30 countries that included information on breastfeeding patterns and other aspects of childbearing for around 50,000 women with invasive breast cancer and around 97,000 women without breast cancer.
Women with breast cancer had fewer children on average (2.2) than women who did not develop breast cancer (2.6). 29% of mothers who developed breast cancer, compared with 21% of those who did not develop breast cancer, had never breastfed; of those women who did breastfeed their children, women who developed breast cancer had a shorter lifetime duration of breastfeeding (around 10 months) compared with women who did not develop breast cancer (16 months).
The relative risk of breast cancer decreased by 4.3% for every year of breastfeeding, in addition to a decrease of 7% for each birth. This pattern of risk was seen consistently for women from developed and developing countries, and for women of different ages and numbers of children.
The investigators estimate that the cumulative incidence of breast cancer in developed countries would be reduced by more than half, from 6.3 to 2.7 per 100 women by age 70, if women had the average number of births and lifetime duration of breastfeeding that had been prevalent in developing countries until recently.
Valerie Beral comments: "The results of this study are a major step forward in our understanding of why breast cancer is so common in developed countries. It has long been known that breast cancer was common in situations where women had few children breastfed for short periods. We have shown that these factors alone account for the high rates of breast cancer in more-developed settings."
Co-author Gillian Reeves adds: "To expect that substantial reductions in breast-cancer incidence could be brought about today by women returning to the pattern of childbearing and breastfeeding that typified most societies until a century or so ago is unrealistic. However, even if women were to breastfeed each of their children for an additional six months, this could prevent about 5% of breast cancers each year."
Reduced breastfeeding in western countries makes major contribution to incidence of breast cancer
Small family size and short-duration or no breastfeeding in Western populations substantially increases the risk of breast cancer, conclude authors of a study in this week's issue of THE LANCET. An estimated 25,000 breast cancers would be prevented in Western populations every year if women continued to have the same number of children but breastfed each child for six months longer.
Childbearing is known to protect against breast cancer; however it has been unclear whether breastfeeding contributes to this protective effect. In an international collaborative study, Valerie Beral from the Cancer Research UK Epidemiology Unit, Oxford, UK, and colleagues pooled and analysed data from 47 epidemiological studies in 30 countries that included information on breastfeeding patterns and other aspects of childbearing for around 50,000 women with invasive breast cancer and around 97,000 women without breast cancer.
Women with breast cancer had fewer children on average (2.2) than women who did not develop breast cancer (2.6). 29% of mothers who developed breast cancer, compared with 21% of those who did not develop breast cancer, had never breastfed; of those women who did breastfeed their children, women who developed breast cancer had a shorter lifetime duration of breastfeeding (around 10 months) compared with women who did not develop breast cancer (16 months).
The relative risk of breast cancer decreased by 4.3% for every year of breastfeeding, in addition to a decrease of 7% for each birth. This pattern of risk was seen consistently for women from developed and developing countries, and for women of different ages and numbers of children.
The investigators estimate that the cumulative incidence of breast cancer in developed countries would be reduced by more than half, from 6.3 to 2.7 per 100 women by age 70, if women had the average number of births and lifetime duration of breastfeeding that had been prevalent in developing countries until recently.
Valerie Beral comments: "The results of this study are a major step forward in our understanding of why breast cancer is so common in developed countries. It has long been known that breast cancer was common in situations where women had few children breastfed for short periods. We have shown that these factors alone account for the high rates of breast cancer in more-developed settings."
Co-author Gillian Reeves adds: "To expect that substantial reductions in breast-cancer incidence could be brought about today by women returning to the pattern of childbearing and breastfeeding that typified most societies until a century or so ago is unrealistic. However, even if women were to breastfeed each of their children for an additional six months, this could prevent about 5% of breast cancers each year."
