Epidemiologic and Surgicopathologic Findings of Papillary Serous and Clear Cell Endometrial Cancers When Compared to Endometrioid Carcinoma

PURPOSE: The aim of this study was to identify similarities and differences in epidemiologic and surgicopathologic staging results for papillary serous (PS) and clear cell (CC) endometrial cancers compared with endometrioid (EM) carcinoma of the endometrium. METHODS: Clinical and surgicopathologic data were retrospectively collected on 574 clinical stage I-II endometrial cancer patients, including 53 PS and 18 CC (based on postoperative histology), undergoing hysterectomy at Duke University Medical Center between 1967 and 1990. All staging material was available and reexamined prior to this analysis, and FIGO surgical staging was retrospectively assigned. PS and CC histologic subtypes were compared both as a common category and as discrete categories versus EM, EM grade 1 (EM1), EM grade 2 (EM2), and EM grade 3 (EM3). Fisher's exact test was used to compare proportions with unordered categories (2x2 tables), while the chi(2) test for trend was used to compare proportions in 3x2 tables with ordered categories. Differences in medians were compared with the Wilcoxon rank-sum test. RESULTS: PS tumors accounted for 8%, CC for 2%, and EM for 90% of cases. Overall, 14% of tumors were changed to a different postoperative histology including 64% of PS, 50% of CC, and 8% of EM. Postoperative histology changes were 4% for EM1 and 21% for EM3. PS, CC, and EM3 had more surgical sampling performed than for other EM. Rates for lymph node dissections were similar for EM3 (81%), PS (72%), and CC (67%) tumors, although metastases were more frequent for PS and CC compared with EM3. When PS tumors were confined to the endometrium, paraaortic metastases occurred in 13%. LVSI increased with EM grade and was highest for PS and CC. Upstaging to surgical stage III-IV occurred in 47% of PS, 39% of CC, and 12% of EM. The majority of PS and CC tumors were confined to the inner one-third of the myometrium, compared with EM tumors, where grade correlated with depth of myometrial invasion. Extrauterine metastases occurred in 55% of PS and 45% of CC tumors confined to the inner one-half, compared with 17% of EM3. CONCLUSION: Frequent changes from preoperative to postoperative histology and grade may contribute to misassignment of preoperative and intraoperative risk as determined by depth of myometrial invasion for PS and CC patients. The higher frequency of extrauterine metastases in PS and CC tumors compared with EM3, despite similar surgical sampling rates, supports a more virulent behavior. The poor correlation between depth of myometrial invasion and risk for extrauterine metastases helps to explain poorer survival in PS and CC patients, in addition to more frequent upstaging. These results support routine extended surgical staging for women with preoperative or intraoperative diagnosis of PS and CC tumors. Intraoperative assessment of tumor grade and histology may be indicated and warrants further investigation.