Background: To assess the clinical impact of the two histological types as designated in the proposed model for ovarian tumourigenesis in primary epithelial ovarian, fallopian tube or peritoneal cancer (EOC) patients.
Methods: All consecutive EOC patients (n=632) after primary tumour debulking in our institution (09/2000-08/2010) were classified into one of two groups: type I tumours (n=100; 15.8%) composed of low-grade serous, low-grade endometrioid, clear cell, mucinous and transitional carcinomas; and Type II tumours (n=532; 84.1%) composed of high-grade serous, high-grade endometrioid, undifferentiated and malignant mixed-mesodermal tumours. Kaplan-Meier and logistic/Cox-regression analyses were performed to assess the impact of histological type on surgical outcome and survival.
Results: Type II patients had a significantly higher incidence of advanced disease (FIGO III/IV) than Type I patients (79.8% vs 38%, respectively; P<0.001). Median CA125 values (438 vs 93 U ml(-1); P=0.001); operative time (258 vs 237 min; P=0.001); and incidence of incomplete tumour resection (34.4% vs 15%; P<0.001) were significantly higher in patients with Type II. During a mean follow-up time of 23 months (range: 1-106), 17% of patients with type I vs 34.8% of patients with type II tumours relapsed and/or died (P<0.001). Overall survival (P=0.021) and progression-free survival (P=0.003) were also significantly higher in patients with type I tumours. Multivariate analysis, while identifying postoperative tumour residuals, positive lymph nodes and extrapelvic dissemination as independent predictors of survival, failed to demonstrate any prognostic significance of histological type.
Conclusion: Type I EOC patients appear to present at earlier stages have significantly higher survival and more optimal surgical outcome compared with type II patients. However, in advanced stages, histology loses significance as an independent prognosticator.