Validation of a two-tier grading system in an unselected, consecutive cohort of serous ovarian cancer patients.

Abstract

New insights into the carcinogenesis of ovarian cancer (OC) lead to the definition of low-grade and high-grade serous OC. In this study, we validated the MD Anderson Cancer Center (MDACC) two-tier grading system and compared it with the traditional three-tier grading system as suggested by the International Federation of Gynecology and Obstetrics (FIGO). Consecutive patients with serous OC were enrolled. These two grading systems were assessed independently from each other. Kaplan-Meier estimates and Cox-regression analyses were performed to validate and compare their prognostic impact. 143 consecutive patients entered the study. According to the Kaplan-Meier estimates, the MDACC grading system (p=0.001) predicted the progression free survival (PFS) more precisely than the FIGO system (p=0.025). The MDACC grading system (p=0.008) but not the FIGO system (p=0.329) showed a statistically significant difference in terms of disease specific survival (DSS). Multivariable Cox-regression analyses revealed an independent prognostic impact of the MDACC grading system but not of the FIGO system for PFS (HR 1.570; 95% CI 1.007-2.449; p=0.047, and HR 0.712; 95% CI 0.476-1.066; p=0.099, respectively). Concerning DSS, the two-tier grading system but not the FIGO system showed a prognostic impact in a univariable Cox-regression analysis (HR 2.152; 95% CI 1.207-3.835; p=0.009, and HR 1.258; 95% CI 0.801-1.975; p=0.319, respectively). We were able to validate the MDACC grading system in serous OC. Moreover, this grading system was stronger associated with survival than the FIGO system.