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.
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 the cancer annually and nearly 8,000 die from the disease. The number of women developing the disease has risen steadily in recent years.
The epidemiologic study, funded by the National Cancer Institute of the National Institutes of Health, gathered data from 668 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.
At any given age, a significant trend was observed between the length of time that a woman was overweight and her risk of endometrial cancer. The longer the time overweight, the higher the risk of endometrial cancer, the study found. The findings are published in this month’s issue of the International Journal of 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 and a professor at the School of Public Health.
After menopause, adipose tissue (which stores fat) converts androgens from the adrenal glands to estrogens without progesterone as is made by the ovaries in the premenopausal years. These “unopposed” estrogens are 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 which are believed to facilitate the process of tumor development.
In general, the risk for endometrial cancer doubles for overweight women compared to women with healthier weights. The risk doubles again for obese women.
Data show that endometrial cancer patients who had substantial weight increases 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 with experienced less than 5 percent weight gain during the same period.
No association between birth weight and endometrial cancer was observed, suggesting that in utero exposure to estrogens or growth factors are not involved in risk of the disease later in life.
Other Yale researchers involved in the study include Drs. Lingeng Lu, Harvey A. Risch, Melinda L. Irwin, Susan T. Mayne, Brenda Cartmel, Peter Schwartz and Thomas Rutherford.