18F-fluorodeoxyglucose positron emission tomography for predicting tumor response to radiochemotherapy in nasopharyngeal carcinoma.

PURPOSE: The aim of this study was to evaluate the value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting tumor response to radiochemotherapy in nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS: From July 2012 to March 2014, 46 NPC patients who had undergone PET scanning before receiving definitive intensity-modulated radiotherapy (IMRT) treatment in our hospital were enrolled. Factors potentially affecting tumor response to treatment were studied by multiple logistic regression analysis.

RESULTS: After radiochemotherapy, 32 patients had a clinical complete response (CR), making the CR rate 69.6%. Multiple logistic regression analysis demonstrated that the maximal standard uptake value (SUV max) of the primary tumor was the only factor related to tumor response (p = 0.001), and that the logistic model had a high positive predictive value (90.6%). The area under the receiver operating characteristic (ROC) curve was 0.809, with a best cutoff threshold at 10.05. Patients with SUV max ≤ 10 had a higher CR rate than those with SUV max > 10 (p < 0.001).

CONCLUSION: The SUV max of the primary tumor before treatment is an independent predictor of tumor response in NPC.