Patterns of failure, treatment outcomes and late toxicities of head and neck cancer in the current era of IMRT

Intensity modulated radiotherapy (IMRT) in head and neck cancer allows sculpting of radiation dose to conform closely to target volumes and spare organs at risk. However, this may be offset by an increased risk of a geographical miss and reduction in survival outcomes. We reviewed the data from 5 prospective randomized controlled trials, one prospective phase II trial and 10 retrospective comparative series in terms of patterns of failure, treatment outcomes and late toxicities to determine any compromise in survival outcomes in favour of reduced late toxicity. Whilst there was some variablility in target volume delineation, radiation dose and technique, the published data consistently show reduced long term xerostomia (ranging from 0.5 to 87%) with IMRT compared to older radiation techniques. Some studies showed reduced incidence of >10% weight loss and grade ≥2 dysphagia with IMRT, and 2 studies reported higher rates of dysphagia with IMRT. Most studies demonstrated better, though non-significant, locoregional, disease-free and overall survival. The 4 studies that did demonstrate significantly better overall survival with IMRT were the largest cohorts with around 250 patients or greater. Standardization of target volume delineation, treatment verification protocols and outcome reporting will reduce heterogeneity and allow data to be pooled in order to be adequately powered for survival analyses.