ObjectiveTo analyze the therapeutic effect and prognostic factors of nasopharyngeal carcinoma (NPC) patients with distant metastases at initial diagnosis receiving induction chemotherapy with intensity-modulated radiotherapy (IMRT).MethodsA total of 129 patients who underwent platinum-based induction chemotherapy followed by definitive IMRT with or without concurrent or adjuvant chemotherapy for newly diagnosed distant metastatic NPC in our center between March 2008 and November 2018 were retrospectively analyzed. 41 patients underwent local therapy for metastatic sites. Kaplan-Meier method was used to estimate survival rates, Log-rank test and Cox proportional hazards model were used to figure out independent prognostic factors of overall survival (OS).ResultsA total of 66 patients had been dead (median follow-up time, 51.5 months). The median overall survival (OS) time was 54.2 months (range, 7-136 months), and the 1-year, 2-year, 3-year, 5-year overall survival rates were 88.0%,71.0%,58.0%, and 47.0%. Multivariate analysis found that the factors correlated with poor overall survival were pre-treatment serum lactate dehydrogenase (SLDH) >180U/L, chemotherapy cycles<4, and M1 stage subdivision (M1b, single hepatic metastasis and/or multiple metastases excluding the liver; and M1c, multiple hepatic metastases). The 5-year OS rates for M1a, M1b and M1c were 62.6%,40.4% and 0%, respectively.ConclusionPlatinum-containing induction chemotherapy combined with IMRT seemed to be advantageous to prolong survival for some NPC patients with synchronous metastases at initial diagnosis. The independent factors to prognosticate OS were pre-treatment SLDH, number of chemotherapy cycles, and M1 subcategories. Prospective clinical trials are needed to confirm the result.
Dosimetric Study on Variations of Gamma Index (GI) in Pre-Treatment Verification Procedure in Intensity Modulated Radiotherapy (IMRT) Plans with Varying Grid Sizes Using 2D Array Detectors