Dosimetric comparison and short-term efficacy analysis of helical tomotherapy and intensity-modulated radiation therapy for locally advanced nasopharyngeal carcinoma

ObjectiveTo compare the dosimetry, acute adverse reactions and short-term therapeutic effects of helical tomotherapy(HT) and intensity-modulated radiation therapy(IMRT) for locally advanced nasopharyngeal carcinoma, and observe the dosimetric advantage, short-term efficacy and adverse reactions of HT in the treatment of locally advanced nasopharyngeal carcinoma.

MethodsThe clinical data of 140 patients with locally advanced nasopharyngeal carcinoma from February 2017 to October 2019 were retrospectively analyzed, which included 70 patients treatment with HT and 70 patients treatment with IMRT.The target area of tumor was delineated according to the magnetic resonance imaging(MRI) of head and neck.The prescription doses of the primary nasopharyngeal carcinoma, metastatic lymph node, high-risk area and low-risk area were 69.96 Gy/33F, 66-70 Gy/33F, 60 Gy/33F and 50-54 Gy/33F, respectively.Two groups were treated with cisplatin based on concurrent chemotherapy at the same time of radiotherapy, with cisplatin dose of 80 mg/m² for a 3-week cycle.The acute adverse reactions of radiotherapy were evaluated according to RTOG/EORTC criteria.The efficacy of solid tumors was evaluated according to RECTST 1.1 criteria.The differences of radiophysical dosimetry, short-term efficacy of patients from the beginning of radiotherapy to 1 month after the end of radiotherapy, and acute adverse reactions related to radiotherapy and chemotherapy were statistically analyzed between two groups.

ResultsIn the prescribed dose, there was no statistical significance in the homogeneity index of target area between the HT group and IMRT group(P>0.05).Among other variables, the conformation number and homogeneity index of target area in HT group were better than that in IMRT group(P < 0.05 to P < 0.01).The short-term efficacy in two groups was similar(P>0.05).The tinnitus and acute parotid gland injury in HT group were less severe than that in IMRT group(P < 0.05).

ConclusionsCompared with IMRT, HT has a better dosimetry advantage in radiotherapy of locally advanced nasopharyngeal carcinoma.Although the short-term efficacy is similar in both groups, HT has less adverse reactions on acute parotid injury and hearing loss.