Postmenopausal Weight Loss Cuts Risk of Endometrial Cancer by Half

An intentional weight loss regimen by postmenopausal obese women can slash their risk of endometrial cancer by 29% to 56%. These observational findings from the Women’s Health Initiative study were published in the Journal of Clinical Oncology.

Endometrial cancer is the fourth most common cancer among women in the United States, and the association between it and obesity has been studied by scientists for a while. However, the effect of weight loss in postmenopausal women and their risk of developing this cancer remains unknown. The choice of the study population is important because more than 75% of endometrial cancers are diagnosed in women 55 and older.

This observational study initially included 93,676 postmenopausal women, between 50 and 79 years old, who were a part of the Women’s Health Initiative. The women, were recruited at 40 clinical centers across the country between September 1, 1993, and December 31, 1998. Information on menopausal hormonal therapy and other covariates of interest was gathered using a combination of questionnaires and personal interviews. Exclusion criteria included:

• History of cancer (except for non-melanoma skin cancer)
• Lack of follow-up information
• Hysterectomy prior to study enrollment
• Missing value of exposures of interest and major confounders
• Endometrial cancer diagnosis, hysterectomy, death, or loss to follow-up between baseline and the year-3 visit

Authors gathered data on 36,793 women to analyze further. Participants’ weight was measured at both the beginning of the study and 3 years later to calculate change in body weight. Women who lost weight were also asked at this time whether their weight loss was voluntary or involuntary.

During a median 11.4-year follow-up, 566 women developed endometrial cancer. The researchers found that women who were successful with their weight loss regimen saw a significant reduction in their risk of endometrial cancer compared with women whose weight remained stable during this period. Furthermore:

• Among women who lost at least 5% of their body weight after age 50, the risk of developing endometrial cancer reduced by 29%, independent of their age or their exact weight loss
• Women who were obese and lost at least 5% of their body weight witnessed a 56% risk reduction
• The risk of developing endometrial cancer was comparable between women with a normal body mass index (BMI) and those who were obese but achieved a normal BMI after and intended weight loss
• A weight gain of 10 pounds or more increase the risk of endometrial cancer by 26%

“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,” study author Juhua Luo, PhD, an associate professor of epidemiology and biostatistics at the Indiana University School of Public Health in Bloomington, Indiana, said in a statement.

The authors hope that their findings will motivate weight loss programs in obese postmenopausal women.

Reference

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.