Weight Gain Later in Life Increases Breast Cancer Risk in Postmenopausal Women

Weight Gain Later in Life Increases Breast Cancer Risk in Postmenopausal Women

According to an article published in the Journal of the American Medical Association, postmenopausal women who have gained weight after the age of 18, or even after menopause, have a significantly increased risk of developing breast cancer. Conversely, postmenopausal women who have lost weight or maintained a healthy weight in their adult life have a significantly decreased risk of developing breast cancer.

Breast cancer is diagnosed in over 200,000 women annually in the U.S.To further understand the causes of breast cancer and improve breast cancer prevention, researchers have explored a variety of factors that may increase or decrease the risk of developing breast cancer. These factors include diet, physical activity, reproductive factors, and hormone use.

Recently, research has emerged indicating that excess weight is associated with an increased risk of developing breast cancer. Studies continue to investigate the relationship between a womans weight and her risk of breast cancer.

Researchers recently evaluated data from the Nurses Health Study, which included over 87,000 postmenopausal women who did not have cancer when the trial began and were followed for up to 26 years. Weight gain since the age of 18 was documented in all of these women; nearly 50,000 had documented weight gain since menopause.

  • A weight gain of 2.0 kg (4.4 lbs) or more since the age of 18 increased the risk of developing breast cancer by 15% after menopause.
  • A weight gain of 2.0 kg or more since menopause increased the risk of developing breast cancer by 4.4% after menopause.
  • Among women who had not used postmenopausal hormones, weight gain since age 18 increased the risk of developing postmenopausal breast cancer by over 24%; weight gain since menopause increased the risk of developing postmenopausal breast cancer by 7.6%
  • Women who have gained 25 kg (55 lbs) or more since the age of 18 had a 45% increased risk of developing breast cancer.
  • There was a greater increase in the risk of developing breast cancer among those with a weight gain of 25 kg or more since the age of 18 if they had never taken postmenopausal hormones.
  • Women who gained 10 kg (22 lbs) or more since menopause had an 18% increased risk of developing breast cancer.
  • Women who had never used postmenopausal hormones and lost 10 kg or more since menopause (and kept the weight off) had 57% reduced risk of developing breast cancer.

The researchers concluded that this study provides further evidence that increased weight significantly increases the risk of developing breast cancer among women. This study indicates that weight gain even in postmenopausal women affects the risk of breast cancer, particularly among women who have not used postmenopausal hormones. Weight loss since the age of 18 and after menopause, however, appears to protect against the development of breast cancer.

Reference: Eliassen A, Colditz G, Rosner B, et al. Adult Weight Change and Risk of Postmenopausal Breast Cancer. Journal of the American Medical Association. 2006; 296:193-201.

Related News:Adult Weight Gain Increases Breast Cancer Risk (5/25/2006)

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