Prognostic value of fluorodeoxyglucose positron emission tomography-computed tomography before and after radiotherapy in locally advanced nasopharyngeal carcinoma

Abstract

Objective To evaluate the prognostic value of maximal standard uptake values ( SUV max ) of flnorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) in pa-tients with locally advanced nasopharyngeal carcinoma (NPC). Methods From October 2002 to January 2004, 58 patients with locally advanced NPC who had undergone FDG PET-CT scan before and after radio-therapy were reviewed retrospectively, FDG uptake of primary tumors and neck nodes represented by SUV max was measured. All patients received intensity-modulated radiotherapy using 6 MV X-rays combined with plat-inum-based chemotherapy. The relation between the change of the SUV max before and after radiotherapy and treatment outcomes was analyzed. Results The median follow-up was 61 (9-69) months. The 5-year over-all survival (OS) and disease-free survival (DFS) were 62% and 53%. The patients with tumor SUV max <8.0 before radiation had a significantly better 5-year OS (80% vs. 49%, χ2 = 5.36 ,P = 0.021 ) and DFS (68% vs. 42% ,χ2 =4.23 ,P =0.040) than those with tumor SU max ≥8.0. The patients who achieved a metabolic complete response (MCR) had significantly higher 5-year OS (74% vs. 46% ,χ2 =5.12,P =0.024) and DFS (65% vs. 38% ,χ2 =5.54,P =0.019) than those who only achieved metabolic partial re-sponse (MPR). Poor prognosis was found in patients with the neck lymph node SUV max higher than that of the primary tumor before radiotherapy ( SUV max-N SUV max-P ) ( χ2 = 4.06, P=0.044 ). Conclusions The SUV max before radiotherapy and metabolic response to radiotherapy may predict the prognosis of paitents with locally advanced NPC. The prognosis is poor for patients with high FDG uptake before and after radiotherapy or SUV max-N SUV max-P . Key words: Nasopharyngeal neoplasms/radiotherapy; Tomography; positron-emission; Fluorodeoxyglucose; Prognosis