Incidence of severe late toxicities of head and neck squamous cell cancer (HNSCC) treatment in the era of intensity modulated radiotherapy (IMRT).

Abstract

e17570 Background: IMRT for HNSCC limits exposure to critical nearby structures thereby reducing toxicities. Real world data on toxicities after long term follow-up post IMRT for HNSCC are lacking. This study assessed the incidence of late toxicities in patients with HNSCC within 5 years post-treatment with definitive IMRT (d-IMRT). Methods: This is a retrospective, IRB approved, single-institution review of patients (pts) with stage I-IVB HNSCC treated with d-IMRT +/- chemotherapy between 2009 and 2013. The primary outcomes were incidence of severe late toxicities (dysphagia requiring esophageal stricture dilation, physician-reported grade 2 or worse neck fibrosis and xerostomia) occurring 3 months or more after completion of IMRT; feeding tube (FT) dependence within 1st year of IMRT completion, and FT dependence beyond 1st year post IMRT. Toxicities were deemed acute if they occurred during IMRT and up to 90 days post IMRT. Results: 274 pts, median age 59 years (38 – 82.9), were identified. 67.6% were HPV positive, 10.5% HPV negative and HPV status was unknown in 21.9%. Site of disease was oropharynx in 70%, larynx in 25% and hypopharynx in 4%. 206 pts (75.2%) received d-IMRT alone, 37 (13.5%) had definitive concurrent chemoradiation – mostly with cisplatin (58%), and 31 (11.3%) received adjuvant IMRT. Of the 243 pts treated with d-IMRT +/- chemotherapy, 80 (32.9%) required FT during RT due to grade 2 or worse acute dysphagia. Excluding 11 pts with disease recurrence or new HNSCC diagnosis, FT dependence at any time from 3 months to one year post IMRT occurred in 22 of 232 pts (9.48%), while FT dependence beyond 1st year post IMRT occurred in 8 pts (3.4%). 11 pts (4.7%) required stricture dilation for late dysphagia. Late grade 2 or worse fibrosis and xerostomia occurred in 7 (3.0%) and 89 (38.4%) pts, respectively. Conclusions: Our study suggests that except for xerostomia, severe late toxicities after definitive IMRT for HNSCC is likely uncommon. Prospective studies with late IMRT toxicities and their impact on quality of life (QoL) as endpoints are warranted.