Background
dysphagia, two-step40, LA-SCCHN, squamous cell carcinoma of the head and neck (, oropharyngeal cancer
DYSPHAGIA, RECURRENCE, ADVERSE EVENTS, OROPHARYNGEAL CANCER, PRIMARY TUMOR
Chemoradiotherapy (CRT) with concurrent high-dose cisplatin (CDDP) is a standard treatment for patients with locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN) [Intensity-modulated radiation therapy (IMRT) has emerged as a current standard method for definitive CRT for LA-SCCHN. Although the advantage of IMRT is its highly conformal dose distribution to the primary tumor and involved lymph nodes with sufficiently low exposure to organs at risk, severe late adverse events after CRT remain a significant problem to be resolved.Several strategies aiming at less invasive CRT using IMRT for LA-SCCHN have been investigated, including (i) reducing the total irradiation dose, (ii) alternative concurrent pharmacotherapy to CDDP, and (iii) reducing the irradiation dose in prophylactic field. However, an increase in local recurrence by using reduced total dose radiation was noted even in HPV-positive oropharyngeal cancer with favorable clinical outcomes [A randomized controlled trial was conducted to investigate reduction of the dose of RT to the elective nodal sites, with 50 Gy in the standard arm and 40 Gy in the experimental arm. The results revealed a trend toward less dysphagia at 6 months in the 40 Gy arm though not statistically significant (38.4% vs. 48.6%), without compromising outcome and survival [Based on these backgrounds, we have launched a randomized controlled trial to confirm the non-inferiority of reduced dose prophylactic radiation with 40 Gy using two-step40 IMRT method (2-step40) to standard dose prophylactic radiation with 56 Gy using simultaneous integrated boost (SIB56) in terms of the time to treatment failure for patients with clinical stage III-IVB (except N3a) LA-SCCHN according to UICC-TNM 8th .