Objective: Because there is no universally accepted grading system for ovarian epithelial carcinoma, we attempted to compare the prognostic utility of the individual components used in some systems--both architectural and cytologic features, as well as mitotic activity and histologic tumor type--to determine which of these components fit best with survival.
Methods: We studied 461 patients with invasive ovarian carcinoma who had uniform treatment, complete clinical data including staging and follow-up, and slides available for review. Each tumor was assigned a histologic subtype, architectural grade (based on whether the predominant pattern was glandular, papillary or solid), nuclear grade, mitotic count, and FIGO grade (based on the system for endometrial carcinoma). These features were compared with each other and with tumor stage and survival.
Results: The architectural grade, nuclear grade, and mitotic count were independent variables both in stage I/II and stage III/IV disease. Each of them correlated with survival for most combinations of histologic type and stage. By multivariate analysis, in stage I/II cancer, nuclear grade and architectural grade were significantly correlated with survival, mitotic count showed only a trend, and FIGO grade did not correlate. In stage III/IV disease, nuclear grade, architectural grade 3, and mitotic count were significant, and FIGO grade was not.
Conclusion: The new architectural grading system proposed worked better than the FIGO system in this study. Furthermore, it could be applied to all histologic subtypes of carcinoma. The nuclear grade and mitotic count were also independent of each other, correlated with survival, and could be utilized for all histologic types. These data support the development of a grading system which combines these architectural, nuclear, and mitotic features and can be applied regardless of the histologic type of carcinoma, modeled after the Nottingham system for grading of breast carcinoma.