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Endometrial carcinoma is the most common malignancy of the female genital tract in the United States. In 1998 there were approximately 36,100 newly diagnosed cases of endometrial carcinoma and 6,300 deaths occurred as a result of this cancer.
Endometrial carcinoma is the most common noncolorectal carcinoma in women belonging to hereditary nonpolyposis colorectal carcinoma (HNPCC) families. Thus, mutations in the DNA mismatch repair genes (hMSH2, hMLH1, hPMS1, and hPMS2) that cause HNPCC are also thought to cause endometrial carcinoma in this setting.
Endometrial carcinoma encompasses two broad categories of malignant epithelial tumors that arise from endometrial epithelium. Epidemiologic and clinical features can distinguish them. Recently, it has been recognized that there are distinct histologic features of endometrial carcinomas that correlate, for the most part, with the two categories. The histologic types are called endometrioid carcinoma and uterine serous carcinoma. Recent molecular studies suggest that there may be differences in the molecular profiles of the two categories of endometrial carcinoma. Furthermore, it is suggested that these molecular differences may contribute to the differences in the clinical behavior of the tumor types.
Approximately 20 percent of sporadic endometrial carcinomas demonstrate microsatellite instability, yet only a fraction of these tumors have mutations in one of the four known DNA mismatch repair genes that cause HNPCC. Microsatellite instability has not been identified in uterine serous carcinomas, and may represent a molecular phenotype confined to endometrioid carcinomas.
The most common molecular abnormalities identified, to date, in endometrial carcinoma are PTEN mutations, microsatellite instability, K-ras mutations, and p53 gene mutations. PTEN is a recently identified tumor-suppressor gene on chromosome 10q23. Mutations in PTEN are the most common molecular alteration yet identified in endometrial cancer with 40–50 percent harboring such mutations. It appears that mutations in PTEN may be important early in the development of endometrioid carcinoma, as they are found in 20 percent of hyperplastic precursor lesions. K-ras mutations are thought to occur in 10–30 percent of endometrial carcinomas, and may also represent a relatively early alteration in endometrioid carcinoma, as mutations are present in atypical hyperplastic lesions.
p53 mutations are found in 10–30 percent of endometrial carcinomas. Recent data suggest that the majority occur in uterine serous carcinoma and in high-grade and high-stage endometrioid carcinomas. p53 mutations are very common in endometrial intraepithelial carcinoma, the precursor of uterine serous carcinoma, and may, therefore, occur early in the pathogenesis of this aggressive type of endometrial carcinoma. Statistical analyses of p53 overexpression by immunohistochemistry have found that it is an independent indicator of poor prognosis.
The molecular genetics of endometrial carcinoma are just beginning to be elucidated. To date, only p53 overexpression offers promise as a useful molecular diagnostic tool.
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Endometrial cancer is the fifth leading cause of cancer in women worldwide, with approximately 150,000 cases diagnosed each year. In the United States, it is the most ...