Testing the validity of a prognostic classification in patients with surgically optimal ovarian carcinoma: a 15-year review.

A retrospectively designed classification using stage, residuum and a variable which combines prognostic information from both grade and histology (histology-grade variable) has been used at our institution to predict prognosis, and choose therapy in patients with ovarian carcinoma, stages I-III having no or small residuum. In this study, multivariate analysis of prognostic factors were performed over two time periods: Group 1 (1971-1978), contains the patients from which the original classification was derived, and Group 2 (1979-1985), contains a different cohort of patients who are used to test the validity and reproducibility of the original classification. Multivariate analysis showed that the prognostic significance of two variables changed over the two study periods: tumor grade, and residuum. It was found that in the ideal combination of grade and histologic type, when used in conjunction with stage and residuum in a prognostic classification, was unique to each patient cohort. Because of these changes, new and more accurate prognostic classifications were derived for Group 2. However, when all classifications were examined, (including the original), the differences in their ability to stratify patients into risk categories was negligible, and there was no major advantage to using one classification over another for clinical applications. Thus, the retrospectively derived prognostic classification using grade, instead of a combined histology-grade variable, in conjunction with the other significant prognostic factors (stage and residuum), is preferred for prospective application, and for its simplicity.