Juhua Luo, PhD
These findings—which draw from the Women’s Health Initiative (WHI) study data—suggest that weight loss could decrease the risk of developing endometrial cancer in postmenopausal patients by as much as 29% to 56%.
“Many older adults think it’s too late to benefit from weight loss, or think that because they are overweight or obese, the damage has already been done. But our findings show that’s not true,” lead study author Juhua Luo, PhD, an associate professor of Epidemiology and Biostatistics at the Indiana University School of Public Health, said in a statement. “It’s never too late, and even moderate weight loss can make a big difference when it comes to cancer risk.”
Compared with women who had stable weight, women with weight loss had a significantly lower endometrial cancer risk (HR, 0.71; 95% CI, 0.54-0.95). This correlation was strongest among obese women who intentionally lost weight (HR, 0.44; 95% CI, 0.25-0.78). Weight gain (≥10 pounds) was associated with a higher endometrial cancer risk than was stable weight, especially among women who had never used hormone therapy.
The trial evaluated over 35,000 women from the WHI Observational Study, which originally enrolled postmenopausal women between the ages of 50 and 79 and was initially designed to address major causes of morbidity and mortality in this specific patient population.
The investigators measured patients’ weight at the beginning of the study and then again 3 years later to assess changes over time. The patients who lost weight were asked via self-report at the 3-year follow-up mark whether their weight loss was intentional or unintentional. Weight change was categorized as stable (change within +/- 5%), loss (change ≥ 5%), and gain (change ≥5%).
The researchers then followed these women for an average of 11.4 years to identify those who were diagnosed with endometrial cancer (n = 566).
The results showed that, among women who lost 5% or more of their body weight after age 50, the risk of developing endometrial cancer was 29% lower, regardless of their age or how much weight they lost.
The greatest reduction of endometrial cancer risk was observed in patients who were obese and intentionally lost weight. Women who were obese and voluntarily lost 5% or more of their body weight saw a 56% reduction in their endometrial cancer risk.
Additionally, women who were overweight or obese and achieved a normal body mass index (BMI) after intentional weight loss were found to have the same risk as women who maintained a stable BMI.
Women who gained more than 10 pounds had a 26% higher risk of being diagnosed with endometrial cancer.
Given that endometrial cancer is known to be highly hormone-related, the study authors also analyzed their findings to determine the influence of hormone use. However, they found no significant difference in risk between women who used hormone therapy and those who did not.
“There have been more than a thousand studies linking obesity to an increased risk of endometrial and other cancers, but almost none that look at the relationship between weight loss and cancer risk,” Jennifer Ligibel, MD, ASCO Expert in Cancer Prevention, said in a statement. “This study tells us that weight loss, even later in life, is linked to a lower risk of endometrial cancer.”
These findings also support the development of weight loss programs that could potentially be embedded within a cancer prevention strategy in overweight and obese adults, explained Ligibel.
According to Karen H. Lu, MD, chair of ASCO’s Cancer Prevention Committee, this study demonstrates the potential role of weight loss in the reduction of cancer risk, as well as the notion that it is never too late to improve one’s health.
“We hope these findings will encourage individuals who may be overweight to change their behaviors to reduce the amount of food eaten and increase their physical activity,” said Lu, chair of ASCO’s Cancer Prevention Committee.
Luo J, Chlebowski RT, Hendryx M, et al. Intentional weight loss and endometrial cancer risk [published online February 6, 2017]. J Clin Oncol. doi:10.1200/JCO.2016.70.5822.