['Previous reports have suggested that patients who have undergone pelvic radiation for cervical cancer are at risk for developing poorly differentiated endometrial cancers with poor prognoses.', 'We conducted a retrospective chart and histologic review of patients from Memorial Sloan-Kettering Cancer Center and MD Anderson Cancer Center diagnosed with endometrial cancer after radiation therapy (RT) for cervical cancer from 1976 to 2000. The comparison group comprised MSKCC endometrial cancer patients whose tumors were not radiation associated ("sporadic cancers").', 'We identified 23 patients who developed endometrial carcinoma or carcinomasarcoma after RT for cervical carcinoma and 527 sporadic endometrial cancer patients. When radiation-associated endometrial cancers (RAECs) were compared with sporadic cancers, significant differences were noted with regard to stage, grade and histologic subtype distribution. In the RAEC group, there were 16 (70%) stages III and IV cancers compared with 101 (19%) in the sporadic group (P<0.001). There were 20 (87%) grade 3 cancers in the RAEC group versus 161 (31%) in the sporadic group (P<0.001). There were 16 (70%) high-risk histologic subtypes (serous, clear cell, carcinosarcoma, undifferentiated) in the RAEC group versus 79 (15%) in the sporadic group (P<0.001). Median survival in the RAEC group was 24 months versus not reached in the sporadic group (P<0.001). Radiation remained a significant factor for poor prognosis in a stratified analysis, in which we compared sporadic and RAEC cancers controlled for age, histology, grade and stage. However, radiation lost significance in a multivariate analysis, in which stage- and grade-matched cancers from both groups were compared.'] Are radiation-associated endometrial cancers prognostically unfavorable tumors : a clinicopathologic comparison with 527 sporadic endometrial cancers?