Organ sparing and clinical outcome with step-and-shoot IMRT for head and neck cancer: a mono-institutional experience

Abstract

Intensity-modulated radiotherapy has been suggested as the technique of choice for locally advanced head and neck cancer patients. In the last decade, most radiotherapy departments have focused their efforts in programs to implement this technique. We report our experience for parotid gland and constrictor muscle sparing with intensity-modulated radiotherapy in head and neck cancer using a step-and-shoot technique. Thirty-four consecutive patients with squamous cell carcinoma of the nasopharynx, oropharynx and larynx treated between June 2008 and June 2011 were retrospectively evaluated. A simultaneous integrated boost was adopted to treat different volumes in 30 fractions over 6 weeks. Priority as organs at risk was given to the parotid glands as well as the constrictor muscle of the pharynx in 53 % (n = 18). Dysphagia and xerostomia were evaluated according to RTOG/EORTC scale at 6, 12 and 24 months. Outcomes were analysed using Kaplan-Meier curves. The median follow-up was 43 months. The 5-year overall survival was 70 %, and local control was 94 %. Grade 2 dysphagia and xerostomia at 6, 12 and 24 months were as follows: 26 % (n = 9), 23 % (n = 8), 23 % (n = 8) and 21 % (n = 7), 12 % (n = 4), 12 % (n = 4), respectively. No grade 3 or 4 toxicity was found. Ordinal logistic regression analysis demonstrated that hyposalivation was the main predictive factor for late dysphagia. Excellent loco-regional results were achieved with acceptable acute and late toxicities. The low rate of late dysphagia was related to parotid gland sparing; we did not observe a correlation between late dysphagia and dose to pharyngeal constrictors.