Short-term curative effect of different dose fractionation patterns of intensity-modulated radiotherapy on nasopharyngeal carcinoma

Objective To study the short-term curative effect of different dose fractionation patterns of intensity-modulated radiotherapy (IMRT) on nasopharyngeal carcinoma (NPC) and its adverse reactions. Methods Ninety-eight NPC patients admitted to our departments from June 2011 to March 2013 were included in this study. The patients underwent helical tomotherapy with modifed dose fractionation patterns at the dose of 67.5 Gy/30 F for pGTV_nx and pGTV_nd, at the dose of 60 Gy/30 F for CTV₁, and at the dose of 54 Gy/30 F for CTV₂, 5 F a week. The short-term curative effect was assessed according to the RECIST 1.0 criteria and the acute reactions were assessed according to the RTOG/EORTC criteria at the end of and 1 month after radiotherapy, respectively. Biological equivalent dose (BED) of the modifed dose fraction patterns was calculated according to the LQ radiobiological model. Results The patients were followed up for 1-22 months (median 12 months). The remission rate of nasopharyngeal primary lesions and positive lymph nodes was 90.8% and 93.9 %, respectively. The incidence of grades 1-2 acute reactions in skin, mucosa, salivary gland and pharynx-esophagus was 92.8%, 89.8%, 96.9% and 98%, respectively. The incidence of grades 3-4 acute reactions in skin, mucosa, salivary gland and pharynx-esophagus was 4.1%, 7.1%, 0% and 2%, respectively. The single fraction was 2.25 Gy, the total dose was 67.5 Gy (30 F/40 d), the BED of the modifed dose fraction patterns was 62.9 Gy, the single BED was 2.5 Gy, and the total BED was 72 Gy for tumor tissue. The single BED was 2 Gy and the total BED was 70 Gy for advanced reactions in normal tissue. Conclusion The short-term curative effect of modifed dose fractionation patterns of intensity-modulated radiotherapy on NPC is rather good with few adverse reactions and a shorter total treatment time which thus decreases the economic cost of patients. However, its long-term curative effect is yet to be further observed.