Epidemiology of Endometrial Cancer
Incidence and mortality
Endometrial cancer is the most common invasive gynecologic cancer in U.S. women, with an estimated 49,560 new cases expected to occur in 2013 and an estimated 8,190 women expected to die of the disease. Endometrial cancer is primarily a disease of postmenopausal women with a mean age at diagnosis of 60 years. Age-adjusted endometrial cancer incidence in the United States has declined since 1975, with a transient increase in incidence occurring from 1973 to 1978, which was associated with estrogen therapy, also known as hormone therapy; there was no associated increase in mortality. From 2005 to 2009, incidence rates of endometrial cancer were stable in white women but increased in African American women by 2.2% per year. The endometrial cancer mortality rates are stable in white women but increased slightly (by 0.4% per year) in African American women from 2005 to 2009. Most cases of endometrial cancer are diagnosed because of symptoms, which are nonetheless “early” stage and have high survival rates.Risk Factors
Estrogen therapy unopposed by progesterone therapy is a cause of endometrial cancer in women with an intact uterus. However, women taking combination estrogen-progesterone therapy (hormone therapy) exhibit similar risk to women who do not take postmenopausal hormone therapy.[4-8] Tamoxifen therapy is also a cause of endometrial cancer. Results from the National Surgical Adjuvant Breast and Bowel Project P-1 trial, report a doubling of the risk of endometrial cancer associated with an annual rate of 2.30 per 1,000 for women taking tamoxifen compared with 0.91 per 1,000 for women receiving placebo; the increased risk was seen primarily in postmenopausal women.
In addition to the increased risk of developing endometrial cancer that is observed in women who use unopposed estrogen therapy or tamoxifen, a number of additional risk factors have been identified, and most appear to be related to estrogenic effects. Among these factors are obesity, a high-fat diet, and reproductive factors such as nulliparity, polycystic ovarian syndrome, early menarche, and late menopause. Hereditary nonpolyposis colorectal cancer (HNPCC) syndrome is associated with a markedly increased risk of endometrial cancer compared with women in the general population. Among women who are HNPCC carriers, the estimated cumulative incidence of endometrial cancer ranges from 20% to 60% by age 70 years (refer to the PDQ summary on Genetics of Colorectal Cancer for more information).[10-12] This risk appears to differ slightly based on the germline mutation; for MLH1 carriers the lifetime risk at age 70 years is 25% while MSH2 mutation carriers have a 35% to 40% lifetime risk of endometrial cancer by age 70 years. The mean age of diagnosis for MLH1 or MSH2 carriers is 47 years compared with 60 years for noninherited forms of endometrial cancer. The prognosis and survival are similar between HNPCC-related and noninherited forms of endometrial cancer.
Major differences exist between black and white women in stages of endometrial cancer at detection and at subsequent survival. Although the incidence of endometrial cancer is lower among black women, mortality is higher. The National Cancer Institute initiated a Black/White Cancer Survival Study  and concluded that higher-grade and more aggressive histologies appear to be related to excess risk of advanced-stage disease in black women. It is difficult to disentangle the effects that biology and socioeconomic status may have on the lower survival rates of African American women with endometrial cancer. Evidence suggests that lower income is associated with advanced-stage disease, lower probability of undergoing a hysterectomy, and lower survival rates. Others, however, assert that there is no black/white difference in the interval from patient-reported symptoms to initial medical consultation, making it unlikely that patient delay after onset of symptoms could explain much of the excess of advanced-stage disease found in black women. Further research is necessary to understand why black women tend to be diagnosed with more aggressive disease and have a higher probability of dying than white women, despite their lower incidence of endometrial cancer.References
- American Cancer Society.: Cancer Facts and Figures 2013. Atlanta, Ga: American Cancer Society, 2013. Available online. Last accessed October 24, 2013.
- American Cancer Society.: Detailed Guide: Endometrial Cancer: What are the Risk Factors for Endometrial Cancer? Atlanta, Ga: American Cancer Society, 2005. Available online. Last accessed February 15, 2013.
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