Weight Gain and Obesity Linked with Endometrial Cancer Risk

Women who put on substantial weight in early adulthood were diagnosed with endometrial cancer at much younger ages than their peers who gained weight later in life, new research by the Yale School of Public Health has found. The findings are published in the International Journal of Cancer.

In addition, long-term obesity significantly increased the risk of this cancer, which develops in the lining of the uterus and is the most commonly diagnosed gynecological cancer in the United States today. Some 42,000 American women are diagnosed with endometrial cancer annually, and nearly 8,000 die from the disease. The number of women developing the disease has risen steadily in recent years.

In general, the risk for endometrial cancer doubles for overweight women compared to women with healthier weights. The risk doubles again for obese women.

Researchers gathered data from 668 endometrial cancer patients and another 665 women of comparable ages without the disease. The heights and weights of the participants were tracked during each decade of adulthood.

Data show that endometrial cancer patients who had a substantial weight increase as young adults tended to be diagnosed at much younger ages. Women in their twenties who experience a weight gain of 35 percent are likely to have endometrial cancer diagnosed 10 years earlier than women who experienced less than 5 percent weight gain during the same period.

A significant trend was also observed between the length of time that a woman was overweight and her risk of endometrial cancer. Women who were consistently overweight between the ages of 20 and 50 had a nearly five-fold increased risk of endometrial cancer. "These data indicate the significant impact of lifestyle in early adult life on health later on," said Herbert Yu, M.D., Ph.D., the study's lead researcher, a professor at the School of Public Health and member of Yale Cancer Center.

After menopause, adipose tissue (which stores fat) produces estrogen but the ovaries no longer make progesterone. The "unopposed" estrogen is believed to play a crucial role in the development of endometrial cancer. Additionally, the fat tissue may have other biological effects on the uterus as it produces growth factors and other molecules which can stimulate cell proliferation and pro-inflammatory reactions that are believed to facilitate the process of tumor development.

Other Yale researchers involved in the study include Yale Cancer Center members Lingeng Lu, Harvey A. Risch, Melinda L. Irwin, Susan T. Mayne, Brenda Cartmel, Peter Schwartz and Thomas Rutherford. The study was funded by the National Cancer Institute.