Proton Beam Radiation for Head and Neck Cancers: A Single-Institution Report on Feasibility and Early Outcomes

Abstract

Definitive radiation of the head and neck has become a mainstay for locally advanced head and neck malignancies. This combined with initial surgery and/or adjuvant chemotherapy yields significant morbidity to the patients both short term and long term. This is a review of our prospective registry database of head and neck patients treated with proton beam radiation at our hybrid community practice/academic proton center to highlight our initial experience with relative long term follow up. All patients in our study were treated with the uniform scanning proton beam technology via the IBA system. Standard fractionation schemes with or without chemotherapy were delivered with curative intent. Acute and late toxicities were assessed by the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0 and the by the Radiation Therapy Oncology Group late radiation morbidity scoring system, respectively. The cumulative incidence of locoregional failure (LRF) was calculated with death as a competing risk. The actuarial freedom from distant metastases (FFDM) and overall survival (OS) rates were calculated with the Kaplan-Meier method. A total of 66 patients were analyzed from our prospective registry. We focused on the 36 de-novo patients as our 30 re-irradiation patients are in process in upcoming literature. The scope of our patient population included patients with malignancies of the paranasal sinuses, nasopharynx, oropharynx, hypopharynx, and major salivary gland. Squamous Cell Carcinoma was the predominant histology, but others were Mucoepidermoid Carcinoma, Adenoid Cystic Carcinoma, Undifferentiated Carcinomas and Esthesioneuroblastomas. The median follow up was 33 months (9 – 53). The 2 and 5 year OS rates were 83% and 75%, respectively. The 2 and 5 year FFDM rates were 92% and 80%, respectively. There was 17% and 25% 2 and 5 year LRF rate. The mean time to failure was 17 months post initial proton beam treatment. Acute grade 3+ toxicity rate was 30.5% (mainly skin, mucositis, odynophagia, dysphagia, and anorexia), while the long term grade 3+ toxicity rate was 6% (anorexia and dysphagia). Ten patients had feeding tubes at some point during the radiation therapy, but none remained on tube feedings beyond 6 months post proton radiation therapy. Proton beam radiation of the head and neck can provide excellent disease control along with great sparing of the OARs. Longer follow up is needed with a less heterogeneous population to validate this modality. In addition, with the advent of intensity modulated proton beam radiation, even better conformality of proton beam will hopefully improve the toxicity profiles of even the acute toxicities.