Incidence and Survival Trends of Uncommon Corpus Uteri Malignancies in the Netherlands, 1989-2008

Introduction: Corpus uteri cancer is the most common malignancy of the female reproductive tract in industrialized countries, and its incidence is increasing. Although most of these tumors are of the common endometrial type, there are also many uncommon tumors of the corpus uteri. We examined the incidence and survival of patients with uncommon epithelial tumors, carcinosarcomas, and sarcomas of the corpus uteri diagnosed since 1989. Methods: All common and uncommon malignancies of the corpus uteri registered in the nationwide population-based Netherlands Cancer Registry (NCR) during 1989-2008 were included (n = 30,960). The histological subtypes were described according to the Blaustein classification system. Age-standardized incidence for 1989-2008 was calculated per 1,000,000 person-years (p-y), and relative survival was calculated according to the type of uncommon tumor. Results: The incidence of corpus uteri malignancies increased from 159 to 177 per 1,000,000 p-y, mainly owing to the rise in endometrioid adenocarcinomas from 106 to 144 per 1,000,000 p-y. In contrast, the incidence of uncommon epithelial endometrial carcinomas (UEECs) decreased from 30 to 13 per 1,000,000 p-y, although carcinosarcomas increased slightly from 5.1 to 6.9 per 1,000,000 p-y. Furthermore, a remarkable shift in incidence of endometrial stromal cell sarcomas (ESS) was observed from high-grade ESSs to low-grade ESSs after 2003. Five-year relative survival for patients with UEEC decreased from 72% to 54% and for patients with serous adenocarcinoma from 73% to 51%. Coinciding with an increase in the incidence of common adenocarcinoma of the corpus uteri, there was a decline in uncommon adenocarcinomas and more or less a stable incidence of sarcomas and carcinosarcomas. Conclusion: The decrease in UEEC tumors consisted largely of fewer serous carcinomas, possibly and likely reflecting a more precise histopathological classification of villoglandular tumors. Unfortunately, relative survival for patients with UEEC, sarcomas, and carcinosarcomas did not improve over the study period, indicating a need for more research on treatment strategies for this group of patients.