Prediction of response to preoperative chemotherapy in adenocarcinomas of the esophagogastric junction by metabolic imaging

Purpose: Preoperative chemotherapy in patients with gastroesophageal cancer is hampered by the lack of reliable predictors of tumor response. This stu dy evaluates whether positron emission tomography (PET) using fluorine-18 f luorodeoxyglucose (FDG) may predict response early in the course of therapy . Patients and Methods: Forty consecutive patients with locally advanced aden ocarcinomas of the esophagogastric junction were studied by FDG-PET at base line and 14 days after initiation of cisplatin-based polychemotherapy. Clin ical response (reduction of tumor length and wall thickness by > 50%) was e valuated after 3 months of therapy using endoscopy and standard imaging:tec hniques. Patients with potentially resectable tumors underwent surgery, and tumor regression was assessed histopathologically. Results: The reduction of tumor FDG uptake (mean +/- 1 SD) after 14 days of therapy was significantly different between responding (-54% +/- 17%) and nonresponding tumors (-15% +/- 21%). Optimal differentiation was achieved b y a cutoff value of 35% reduction of initial FDG uptake. Applying this cuto ff value as a criterion for a metabolic response predicted clinical respons e with a sensitivity and specificity of 93% (14 of 15 patients) and 95% (21 of 22), respectively. Histopathologically complete or subtotal tumor regre ssion was achieved in 53% (eight of 15) of the patients with a metabolic re sponse but only in 5% (one of 22) of the patients without a metabolic respo nse. Patients without a metabolic response were also characterized by signi ficantly shorter time to progression/recurrence (P = .01) and shorter overa ll survival (P = .04). Conclusion: PET imaging may differentiate responding and nonresponding tumo rs early in the course of therapy. By avoiding ineffective and potentially harmful treatment, this may markedly facilitate the use of preoperative the rapy, especially in patients with potentially resectable tumors. J Clin Onc ol 79:3058-3065. (C) 2001 by American Society of Clinical Oncology.