A randomized phase III study between sequential versus simultaneous integrated boost intensity-modulated radiation therapy in nasopharyngeal carcinoma

This study was performed to compare the acute and late toxicities between sequential (SEQ) and simultaneous integrated boost (SIB) intensity-modulated radiotherapy (IMRT) in nasopharyngeal carcinoma (NPC). Stage I-IVB NPC patients were randomized to receive SEQ-IMRT or SIB-IMRT. SEQ-IMRT consisted of two plans: 2 Gy x 25 fractions to low-risk planning target volume (PTV) followed by a sequential boost (2 Gy x 10 fractions) to high-risk PTV, while SIB-IMRT treated low- and high-risk PTVs with doses of 56 and 70 Gy in 33 fractions. Toxicities and survival outcomes were analyzed. Between October 2010 and September 2015, of the 209 patients who completed treatment, 102 in the SEQ and 107 in the SIB arm were analyzed. The majority had undifferentiated squamous cell carcinoma (82%). Mucositis and dysphagia were the most common grade 3-5 acute toxicities. There were no statistically significant differences in the cumulative incidence of grade 3-4 acute toxicities between the two arms (59.8% in SEQ vs. 58.9% in SIB; P = 0.892). Common grade 3-4 late toxicities for SEQ and SIB included hearing loss (2.9 vs. 8.4%), temporal lobe injury (2.9 vs. 0.9%), cranial nerve injury (0 vs. 2.8%), and xerostomia (2 vs. 0.9%). With the median follow-up of 41 months, 3-year progression-free and overall survival rates were 72.7 vs. 73.4% (P = 0.488) and 86.3 vs. 83.6% (P = 0.938), respectively. SEQ and SIB provide excellent survival outcomes with few late toxicities. According to our study, SIB with a satisfactory dose-volume constraint to nearby critical organs is the technique of choice for NPC treatment due to its convenience. (orig.)