Significant Weight Gain in Adulthood Increased Risk for Endometrial Cancer

Postmenopausal women who gained weight during adulthood had an increased risk for endometrial cancer compared with women who maintained a stable weight, according to data from the American Cancer Society’s Cancer Prevention Study II Nutrition Cohort.

Victoria L. Stevens, Ph.D., strategic director of laboratory services at the National Home Office of the American Cancer Society in Atlanta, presented the data at the 10th AACR International Conference on Frontiers in Cancer Prevention Research, held Oct. 22-25, 2011.

Stevens and colleagues investigated whether adulthood weight gain and/or weight cycling, defined as the number of times a woman purposefully lost 10 pounds or more and then later regained the weight, increased the risk for endometrial cancer in postmenopausal women, independent of body mass index (BMI). Weight cycling, commonly referred to as “yo-yo” dieting, had previously been suggested to increase the amount of fat mass relative to lean body mass, according to Stevens.

“Fat tissue is the major source of circulating estrogen in postmenopausal women, and estrogen promotes the development of endometrial cancer,” Stevens said. “Therefore, we hypothesized that weight cycling could be associated with risk for this cancer because women who engage in this behavior may have a higher proportion of fat than noncyclers.”

The researchers collected data from 38,152 women with an intact uterus and who provided information on weight history and weight cycling on a 1992 questionnaire. Between 1992 and 2007, 560 women reported a diagnosis of endometrial cancer.

Overall, the results indicated that there was an almost fourfold increased risk for endometrial cancer in women who had gained 61 pounds or more in that timeframe, compared with women who maintained a stable weight. After adjustment for baseline BMI, the researchers found a twofold increased risk for endometrial cancer.

Endometrial Cancer Risk Factors Before menopause, the ovaries normally produce two main types of hormones: estrogen and progesterone. Estrogen promotes endometrial cell growth; progesterone inhibits it. Endometrial cancer is more common in women who have consistently high circulating levels of estrogen and low levels of progesterone. Any factor that leads to increased relative exposure to estrogen over time also leads to an increased risk of endometrial cancer.

The key risk factors for endometrial cancer are:

* obesity - particularly being more than 50 pounds overweight (fat tissue can convert other hormones in the body into estrogens)
* early menstruation (periods starting before age 12)
* late menopause (after age 52)
* never having given birth or a history of infertility (an inability to become pregnant)
* ovarian diseases, such as polycystic ovaries, that may cause a woman to have higher-than-normal estrogen levels and lower-than-normal progesterone levels* tamoxifen use