Weight Gain Prevalent in Breast Cancer Survivors
Breast cancer survivors with a familial risk appear to have a high risk of gaining excess weight, according to new data.
Women with a family history of the disease, including those who carry BRCA1 and BRCA2 gene mutations, gained weight at a greater rate than cancer-free women of the same age and menopausal status.
Researchers from Johns Hopkins Kimmel Cancer Center in Baltimore, Maryland, compared weight gain in 303 breast cancer survivors and 307 controls (cancer-free women matched for age and menopausal status). They found that within a 5-year time frame, survivors gained an average of 3.81 pounds, which was significantly more than weight gained in the control group.
Survivors who had received chemotherapy (with or without hormonal therapy) had even greater weight gains. Of the women treated with chemotherapy within 5 years from baseline, 21% gained at least 11 pounds during the follow-up period.
The study was published online July 15 in Cancer Epidemiology, Biomarkers & Prevention.
“Even after controlling for all confounders, we saw increased weight gain,” said lead author Kala Visvanathan, MD, MHS, director of the Clinical Cancer Genetics and Prevention Service at the Sidney Kimmel Comprehensive Cancer Center.
“All of the women in this study had a family history of breast cancer because we were trying to compare women who were very similar,” she said in an interview with Medscape Medical News. “They have unique characteristics, and this makes them more comparable.”
The take-home message for clinicians is that both the physicians and the women should recognize the risk for weight gain and monitor weight, explained Dr Visvanathan. “They should be followed over time and then we need to act upon it if the woman is putting on weight. We need to be providing encouragement to women to optimize their weight post treatment.”
One of the things that Dr Visvanathan and her team are doing is following these women for a longer period so they can get a better idea of the patterns of weight gain. “We need additional studies to understand the underlying mechanism,” she said.
It is possible that these results could apply to a general population of patients with breast cancer, Dr Visvanathan added, but there aren’t any data yet for populations outside of this specific group.
Weight Gain Higher Among Survivors
Previous studies have reported weight gain in cancer survivors and a negative effect of weight gain on survival. However, it is unclear whether survivors gained more weight compared with cancer-free women of similar age and menopausal status.
The authors noted that weight gain and higher body mass index have been associated with an increased risk for a second primary cancer, as well as increasing the risk for breast cancer recurrence.
Dr Visvanathan and her team examined whether breast cancer survivors with a familial risk experienced a greater weight gain after their diagnosis compared with controls without cancer.
They recruited 303 breast cancer survivors and 307 women without cancer matched for age and menopausal status from the Breast and Ovarian Surveillance Service cohort study, which is composed of women with familial risks for breast and ovarian cancer, including BRCA1/2 mutation carriers.
The average age of survivors and menopausal status was similar between the two study groups; 25% of participants were premenopausal in each group. Among those tested (n = 357) , BRCA1/2 mutation carrier status was also similar between groups.
Participants completed a baseline questionnaire (the time point referred to as T1) and at least one follow-up questionnaire, which was administered every 3 or 4 years. The authors then computed weight gain using data from T1 and follow-up questionnaires.
The prevalence of overweight/obesity in the cohort was high overall in both women who were cancer free (55.1%) and the survivors (46.9%).
Chemo and Statins Boost Weight Gain
Overall, the authors found that breast cancer survivors gained weight at a greater rate than did the cancer-free controls, particularly if they had received chemotherapy for an estrogen receptor (ER)–negative tumor or were within 5 years of their diagnosis.
Women who were diagnosed with breast cancer within 5 years before T1 had gained an average of 3.81 pounds more than the controls, and those with ER-negative disease had gained an average of 7.26 pounds more than cancer-free women.
No significant weight gain was observed among women who were diagnosed with breast cancer more than 5 years before T1 or who had received hormonal therapy for ER-positive disease.
The authors also looked at the effects of treatment on weight gain. Women who received adjuvant chemotherapy with or without hormone therapy had a significant average weight gain of 4.26 pounds, and those who received chemotherapy alone had an even greater weight gain of 7.86 pounds.
The greatest weight gain was observed in women who used statin drugs and who received chemotherapy. Their weight gain was higher than that in cancer-free women who used statins, survivors who received chemotherapy but no statins, and cancer-free women who never used a statin (P for interaction = .01).
“This is an interesting study, as we know that excess body fat after menopause can contribute to breast cancer and possibly recurrence,” commented Alice Chung, MD, a surgical oncologist in the Saul and Joyce Brandman Breast Center at the Cedars-Sinai Samuel Oschin Comprehensive Cancer Institute, Los Angeles, California.
“This study raises an important issue, but there are a lot of potential confounding factors that may affect a women’s body weight other than having cancer treatment,” she told Medscape Medical News. “It is difficult to account for all of those factors with this kind of a study design. So it is unclear how reliable the authors conclusions are but it definitely presents a topic worth investigating further.”
Cancer Epidemiol Biomarkers Prev. Published online July 15, 2015. Abstract