Pretreatment ¹⁸F-FDG PET standardized uptake value of primary tumor and neck lymph nodes as a predictor of distant metastasis for patients with nasopharyngeal carcinoma

Objectives: To evaluate the prognostic value of maximum standardized uptake value (SUVmax) measured in [¹⁸F]-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) for patients with non-disseminated nasopharyngeal carcinoma (NPC). Materials and methods: From January 2002 to July 2008, 371 NPC patients who underwent ¹⁸F-FDG-PET before radical intensity-modulated radiotherapy (IMRT) were recruited. The SUVmax was recorded for the primary tumor (SUVmax-T) and neck lymph nodes (SUVmax-N). Results: The median follow-up was 64 months. The optimal cutoff value was 9.3 for SUVmax-T and 7.4 for SUVmax-N. Patients with a lower SUVmax-T or SUVmax-N had a significantly better 5-year distant metastasis-free survival (DMFS), but showed no significant difference in local control or regional control. Patients were divided into four groups by SUVmax, as follows: (a) both lower SUVmax-T and SUVmax-N, (b) higher SUVmax-T only, (c) higher SUVmax-N only, and d) both higher SUVmax-T and SUVmax-N. There were significant differences between these four groups in 5-year DMFS: (a) 95.5%, (b) 90.0%, (c) 83.3%, and (d) 79.9%, respectively (p = 0.004). When looking at the stage of disease, the 5-year DMFSs in group a, b, c, d were 96.9%, 94.6%, 97.4%, and 84.3%, respectively in stage I-III patients (p = 0.037) and were 91.6%, 82.9%, 68.5%, and 76.7% in stage IVA-B patients (p = 0.145). Using multivariate analysis, the SUVmax grouping, gender, and stage were independent factors for DMFS. Conclusion: The SUVmax of the primary tumor and neck lymph nodes were independent prognostic factors for DMFS in NPC patients treated with IMRT.