Weight Cycling and Risk of Endometrial Cancer

Abstract

Background: Obesity, as measured by body mass index (BMI), is an established risk factor for endometrial cancer in postmenopausal women. Weight cycling, which consists of repeated cycles of weight loss followed by regain, occurs frequently in overweight and obese women. It is unclear whether weight cycling is associated with risk of endometrial cancer independent of BMI.Methods: This analysis included 38,148 postmenopausal women enrolled in the Cancer Prevention Study II Nutrition Cohort, of whom 559 were diagnosed with endometrial cancer between enrollment in 1992 and June 30, 2007. Number of lifetime weight cycles was determined from questions on the baseline questionnaire asking how many times 10 or more pounds were intentionally lost and later regained. Multivariable-adjusted hazard rate ratios (RR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression.Results: Weight cycling was positively associated with endometrial cancer incidence (RR, 2.13; 95% CI, 1.63-2.78 for 10þ weight cycles vs. no weight cycles; P trend < 0.0001). However, after adjustment for BMI in 1992, this association was null (RR, 1.05; 95% CI, 0.77-1.42; P trend ¼ 0.82). Weight cycling was not associated with endometrial cancer in analyses stratified by BMI or by weight change after adjustment for BMI.Conclusions: After adjustment for BMI, weight cycling was not associated with the risk of endometrial cancer.Impact: These findings suggest that weight loss with subsequent regain is unlikely to increase risk of endometrial cancer. Therefore, weight loss for better health should be encouraged. Cancer Epidemiol Biomarkers Prev; 21(5); 747-52. Ó2012 AACR.

Weight Fluctuation and Cancer Risk in Postmenopausal Women: The Women's Health Initiative

“…Additionally, our weight cycling findings align with some(13,15,16), but not all(18,20–22), prior studies suggesting a positive association between weight cycling and endometrial cancer incidence. For instance, three case control studies show a two(15) to three(13,16) –fold increase in the odds of weight cycling in women who developed endometrial cancer, compared to those who were cancer free.…”

“…For instance, three case control studies show a two(15) to three(13,16) –fold increase in the odds of weight cycling in women who developed endometrial cancer, compared to those who were cancer free. Likewise, two(18,22) (of three(20)) prospective cohort studies suggest a positive association between weight cycling and endometrial cancer risk, with hazard ratios ranging from 1.06(18) to 2.13(22) compared to non-cyclers, prior to BMI adjustment. All prior studies assessing the association between weight cycling and breast(18,20,21) and colorectal(18,20) risk in postmenopausal women present null findings, which is in agreement with our findings.…”

“…All prior studies assessing the association between weight cycling and breast(18,20,21) and colorectal(18,20) risk in postmenopausal women present null findings, which is in agreement with our findings. In most studies, positive results were attenuated to non-significance after adjustment for baseline BMI or body weight(15,16,18,22). However, our findings suggest prior weight gain and weight cycling increase breast and endometrial cancer risk, respectively.…”

“…Correlations between recalled weight and objectively measured weight gradually decrease over time(57), and may be underestimated more so among women(58) and heavier individuals(59). Despite this, many similar studies(11–16,18,20–22) use self-reported recall data to report weight cycling exposure. The quality of weight-change data was somewhat limited in that specific magnitude and rate of weight loss and regain, as well as timing of weight cycles throughout adulthood was not evaluated.…”

“…However, in many cases, modest findings are attenuated after adjustment for current weight/BMI(15–18). In addition, robust evidence from longitudinal cohort studies is limited and disparate(11,18,20,22), with few studies reporting on breast(18,20,21) and colon/colorectal(18,20) cancer outcomes.…”