18F-FDG PET/CT for monitoring induction chemotherapy in patients with primary inoperable penile carcinoma: first clinical results.

ABSTRACT

PURPOSE: The aim of this study was to explore the role of (18)F-FDG PET/CT for monitoring treatment response in patients with primary inoperable (i.e. advanced) penile carcinoma treated with induction chemotherapy and to compare the metabolic tumour response with the radiological evaluation provided by CT imaging. METHODS: Eight patients with advanced penile carcinoma were studied. All had undergone (18)F-FDG PET/CT imaging at baseline and after two cycles of induction chemotherapy. The metabolic tumour response was evaluated according to European Organisation for Research and Treatment of Cancer (EORTC) criteria for therapy response. The radiologic tumour response was assessed using the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines. Response evaluations were done separately and blinded for other patient data. For definition of the reference, all patients were rated as responders or non-responders by a multidisciplinary tumour board. RESULTS: PET/CT showed hypermetabolic uptake of FDG matching with malignancy in all eight patients. According to the reference, six patients were responders and two non-responders after two cycles of chemotherapy. The metabolic tumour response was considered accurate in all eight patients. In seven of the eight patients, the radiological tumour response was in agreement. In three patients correctly identified as responders, the radiological tumour response was deemed suboptimal compared with the metabolic assessment. Five of the six responders continued chemotherapy after response evaluation up to four cycles and were operated subsequently. Histopathological analysis confirmed the metabolic tumour response. CONCLUSION: (18)F-FDG PET/CT imaging is feasible for monitoring response in patients with advanced penile carcinoma treated with induction chemotherapy. Our preliminary results suggest that PET/CT is potentially more reliable than CT alone.