Enhancing Fraction Predicts Clinical Outcome following First-Line Chemotherapy in Patients with Epithelial Ovarian Carcinoma

Purpose: To define a simple radiologic biomarker of prognosis in patients with advanced epithelial ovarian carcinoma on first-line chemotherapy. Experimental Design: Twenty-seven patients receiving platinum-based chemotherapy with >2 cm residual disease [International Federation of Gynecology and Obstetrics (FIGO) stages IIIC or IV] after surgery were identified. The proportion of enhancing tumor tissue—the enhancing fraction—was calculated on pre-chemotherapy computed tomography scans at four Hounsfield unit (HU) thresholds and assessed for correlation with CA125 response, Response Evaluation Criteria in Solid Tumors (RECIST) radiologic response, and time to progression. Discriminative power was assessed by leave-one-out discriminant analysis. Results: Pre-chemotherapy residual tumor volume did not correlate with clinical outcome. Pre-chemotherapy enhancing fraction at all thresholds significantly correlated with CA125 response (P < 0.001, ρ = 0.553 for 50 HU; P < 0.001, ρ = 0.565 for 60 HU; P < 0.001, ρ = 0.553 for 70 HU; P = 0.001, ρ = 0.516 for 80 HU). Significant correlations were also shown for radiologic response at all thresholds. Enhancing fraction predicted CA125 response with 81.9% to 86.4% specificity and Response Evaluation Criteria in Solid Tumors response with 74.9% to 76.8% specificity at 95% sensitivity (dependent on threshold). Enhancing fraction correlated with time to progression at the 60 HU (P = 0.045, ρ = 0.336) and 70 HU (P = 0.042; ρ = 0.340) thresholds. Conclusion: Pre-chemotherapy enhancing fraction is a simple quantitative radiologic measure. Further evaluation in larger trials is required to confirm the potential of enhancing fraction as a predictive factor, particularly for patients who may benefit from the addition of antiangiogenic therapy.