Comparison Of Long-Term Survival And Toxicity Of Simultaneous Integrated Boost Versus Conventional Fractionation With Intensity-modulated Radiotherapy For The Treatment Of Nasopharyngeal Carcinoma

Objective: In recent years, the intensity-modulated radiotherapy with simultaneous integrated boost(IMRT-SIB) and intensity-modulated radiotherapy with conventional fractionation(IMRT-CF) have been involved in the treatment of nasopharyngeal carcinoma(NPC). However, the potential clinical effects and toxicities are still controversial.Methods: Here, One-hundred and seven patients with biopsy-proven locally advanced NPC between March 2004 and January 2011 were enrolled in the retrospective study. Among them, 54 patients received IMRT-SIB, and 53 patients received IMRT-CF. Subsequently, overall survival(OS), 5-year progression-free survival(PFS), 5-years locoregional free survival(LRFS), and relevant toxicities were analyzed.Results: In the present study, all patients completed the treatment, and the overall median follow-up time was 80 months(range, 8–126 months). The 5-year OS analysis revealed no significant difference between the IMRT-SIB and IMRT-CF groups(80.9% vs. 80.5%, P=0.568). In addition, there were also no significant between-group differences in 5-year PFS(73.3% vs. 74.4%, P=0.773) and 5-years LRFS(88.1% vs. 90.8%, P=0.903). Notably, the dose to critical organs(spinal cord, brainstem and parotid gland) in patients treated by IMRT-CF was significantly lower than that in patients treated by IMRT-SIB(all P<0.05).Conclusions: Both IMRT-SIB and IMRT-CF techniques are effective in treating locally advanced NPC, with similar OS, PFS, and LRFS. However, IMRT-CF has more advantages than IMRT-SIB in protecting spinal cord, brainstem and parotid gland from acute and late toxicities, such as xerostomia. Further prospective study is warrant to confirm our findings.