Revised June 2011

Risk Factors:

This cancer is the fourth most common malignancy diagnosed in BC. Most are adenocarcinomas. The incidence rate for this cancer increased during the 1970s but has since slightly declined (National Cancer Institute of Canada, 1998). This feature perhaps reflects the pattern of estrogen replacement therapy usage by women.

Use of combination oral contraceptives prior to menopause appears to lower risk of endometrial cancer, and the effect persists for a number of years after discontinuing such medication. High levels of estrogen exposure, unopposed by progesterone, as found in some menopausal hormone replacement therapy, appears to be strongly related to the risk of developing this cancer (Kelsey and Whittemore, 1994). Later age at menopause has also been identified as a risk factor. Nulliparous women have been shown to have a two-to-three fold increased risk of developing this cancer in several studies. Obesity has been associated with increased risk, perhaps due to changes in estrogen metabolism. There is evidence that high dietary fat intake increases risk. Two major types of endometrial cancer are now recognized:
Type1 – less aggressive, younger patients, estrogen excess scenario, PTEN mutations.
Type 2 – older, thinner, aggressive, often papillary serous. p53 mutations.

Endometrial cancer is also seen as part of the Lynch syndrome (Hereditary non-polyposis coli, secondary to abnormalities of mismatch repair genes): colon cancer, prostate, endometrium, ovary, stomach, small bowel, pancreas, hepatobiliary and renal pelvis-ureter.

Prevention:

With respect to prevention, weight loss in obese women may have the most potential for reducing risk. The use of combination oral contraceptives may also reduce risk. The addition of progesterone to estrogen replacement therapy appears to counteract the adverse effects of unopposed estrogen on the uterus. However, long-term use of oral contraceptives and estrogen replacement therapy may increase the risk of breast cancer. Hence caution should be exercised with preventive measures involving hormones (Miller, 1992).

References:

1. Kelsey J, Whittemore AS. Epidemiology and primary prevention of cancers of the breast, endometrium and ovary: a brief review. Ann Epidemiology 1994;4:89-95.
2. Miller AB. Planning cancer control strategies. Chronic Dis Can 1992;13:S1-S40.