TOWARD THE DEVELOPMENT OF A UNIVERSAL GRADING SYSTEM FOR OVARIAN EPITHELIAL CARCINOMA - TESTING OF A PROPOSED SYSTEM IN A SERIES OF 461 PATIENTS WITH UNIFORM TREATMENT AND FOLLOW-UP

BACKGROUND. Most published series of ovarian carcinoma find a correlat ion between histologic grade and survival, but the grading system used commonly is not specified, and several different systems exist, some of which use different criteria for different histologic types. Howeve r, several studies have shown marked interobserver variability in dist inguishing among the histologic types of ovarian carcinoma. The author s attempted to derive a universal grading system for all invasive ovar ian carcinomas (IOC), based on the Nottingham system for grading all t ypes of mammary carcinoma. METHODS. The authors studied 461 patients w ith IOC of different histologic types and clinicopathologic stages who were treated in a uniform manner between 1980 and 1994 with surgery a nd cisplatin-based chemotherapy. AU slides were reviewed and the tumor s graded as follows: Architectural pattern (predominant): Glandular = 1, Papillary = 2, and Solid = 3; Nuclear pleomorphism: Slight = 1, Mod erate = 2, and Marked = 3; Mitotic activity (mitotic figures per 10 hi gh-power fields [1 HPF = 0.345 mm(2)]) in most active region: 0-9 = 1, 10-24 = 2, and greater than or equal to 25 = 3; Grade 1 = total score (adding three values obtained earlier) 3-5, Grade 2 = 6 or 7, and Gra de 3 = 8 or 9. RESULTS. Tumor grade correlated with survival in both e arly and advanced stage disease and for all major histologic types of IOC except clear cell carcinoma (CCC). Results for CCC approached but did not reach clinical significance. By multivariate analysis, only th is tumor grade and performance status were significant in Stage I/II I OC. For Stage III/IV tumors, the new tumor grade also was significant, as were performance status, residual tumor size, response to chemothe rapy, and mucinous (unfavorable) or transitional cell (favorable) hist ologic type. International Federation of Gynecology and Obstetrics gra de (based primarily on architectural features) did not correlate signi ficantly with survival except in Stage III/IV serous and Stage I/II mu cinous carcinomas. CONCLUSIONS. The new grading system reported is sim ple, reproducible (among the current study authors), and useful for al l histologic types and clinical stages of IOC. Further testing for rep roducibility and clinical utility is recommended. (C) 1998 American Ca ncer Society.