New research suggests that breast cancer survivors, particularly those who went through chemotherapy, are more prone to weight gain.
The study, conducted by researchers at the Johns Hopkins Kimmel Cancer Center, found that breast cancer survivors gained more weight—3.6 pounds on average—than cancer-free women over a four-year period. Furthermore, survivors treated with chemotherapy were 2.1 times more likely than cancer-free women to gain at least 11 pounds during follow-up. A family predisposition for breast cancer increased that risk.
The study, published in the July 15 issue of Cancer Epidemiology, Biomarkers & Prevention, adds to a growing body of research linking chemotherapy to weight gain in cancer survivors.
Study author Kala Visvanathan, a professor of epidemiology at JHU's Bloomberg School of Public Health, cautioned that the results don't suggest the need for weight gain intervention during chemotherapy. But she said doctors treating breast cancer survivors can "help them monitor their weight over the long term."
Visvanathan, who also directs the Clinical Cancer Genetics and Prevention Service at the Kimmel Cancer Center, noted that it's not clear why chemotherapy treatment produces this effect. Some research suggests that chemotherapy increases inflammation and insulin resistance, disrupting metabolism. Chemotherapy patients also may be less physically active and therefore more prone to weight gain.
The study also linked weight gain in breast cancer survivors to other factors, including the use of cholesterol-blocking statins and the presence of invasive disease and cancer cells lacking receptors for estrogen.
Researchers also found that regardless of their cancer status, women with a family history or inherited predisposition for breast cancer were more likely to be overweight or obese.
Between 2005 and 2013, researchers looked at 303 breast cancer survivors and 307 cancer-free women. The weight change findings remained the same after accounting for other factors like increasing age, menopause, and level of physical activity.
The findings are particularly relevant because previous studies suggest that breast cancer survivors who gain weight are at greater risk for cancer recurrence.