Adapted from the NCI Cancer Bulletin ¹.

Results of a retrospective analysis of more than 21,000 women with early-stage endometrial cancer demonstrate a significant survival benefit with adjuvant radiation therapy (RT) in subsets of women with high-risk disease. Overall and relative survival were significantly improved in women with stage IC disease with tumor grades 1, 3, and 4, compared with women who did not receive adjuvant therapy. The study appears in the January 25 Journal of the American Medical Association (see the journal abstract).

As opposed to stage IA, in which the tumor is within the inner lining of the uterus, stage IC endometrial cancer has spread into the outer portion of the myometrium, the layer of muscle around the uterus. The higher the grade of the tumor, the more malignant it is considered to be. However, early-stage endometrial cancer is considered to be highly curable with surgery and recurrence risk is generally low.

To conduct the study, Dr. David Gaffney of the Huntsman Cancer Institute and University of Utah Medical Center, analyzed data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program on women with stage IA through IC node-negative endometrial adenocarcinoma. Approximately 19 percent of patients were treated with adjuvant RT.

Previous studies have shown variable results in women with early-stage disease at intermediate and high risk, according to Dr. Gaffney and his colleagues, demonstrating improvements in local control and/or disease-free survival, but not in overall survival. This may be because the prior randomized trials have had "poor accrual and insufficient patient numbers at the time of analysis," they commented.

"To our knowledge, as the largest reported population analysis of the use of adjuvant radiation therapy in early-stage endometrial adenocarcinoma to date, it is significant that our study reveals an association in both overall survival and relative survival for adjuvant RT in stage IC disease (grades 1 and 3-4 cohorts)," they wrote.

Dr. Ted Trimble of National Cancer Institute's Division of Cancer Treatment and Diagnosis, called the study results "provocative," but cautioned that more information is still needed to determine which early-stage patients are at highest risk for recurrence after surgery and how best to treat them. The National Cancer Institute is planning an endometrial cancer state-of-the-science meeting for late 2006, he said, to help plan future treatment studies.

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