Proton beam radiation therapy results in significantly reduced toxicity compared with intensity-modulated radiation therapy for head and neck tumors that require ipsilateral radiation

Abstract

Background As proton beam radiation therapy (PBRT) may allow greater normal tissue sparing when compared with intensity-modulated radiation therapy (IMRT), we compared the dosimetry and treatment-related toxicities between patients treated to the ipsilateral head and neck with either PBRT or IMRT. Methods Between 01/2011 and 03/2014, 41 consecutive patients underwent ipsilateral irradiation for major salivary gland cancer or cutaneous squamous cell carcinoma. The availability of PBRT, during this period, resulted in an immediate shift in practice from IMRT to PBRT, without any change in target delineation. Acute toxicities were assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. Results Twenty-three (56.1%) patients were treated with IMRT and 18 (43.9%) with PBRT. The groups were balanced in terms of baseline, treatment, and target volume characteristics. IMRT plans had a greater median maximum brainstem (29.7 Gy vs. 0.62 Gy (RBE), P < 0.001), maximum spinal cord (36.3 Gy vs. 1.88 Gy (RBE), P < 0.001), mean oral cavity (20.6 Gy vs. 0.94 Gy (RBE), P < 0.001), mean contralateral parotid (1.4 Gy vs. 0.0 Gy (RBE), P < 0.001), and mean contralateral submandibular (4.1 Gy vs. 0.0 Gy (RBE), P < 0.001) dose when compared to PBRT plans. PBRT had significantly lower rates of grade 2 or greater acute dysgeusia (5.6% vs. 65.2%, P < 0.001), mucositis (16.7% vs. 52.2%, P = 0.019), and nausea (11.1% vs. 56.5%, P = 0.003). Conclusions The unique properties of PBRT allow greater normal tissue sparing without sacrificing target coverage when irradiating the ipsilateral head and neck. This dosimetric advantage seemingly translates into lower rates of acute treatment-related toxicity.

Disparities in radiation therapy delivery: current evidence and future directions in head and neck cancer

“…Both modalities have been associated with significant improvements in toxicities and quality-of-life [7][8][9], with one retrospective study even suggesting a cancer-specific survival benefit to intensitymodulated radiation therapy over 3D-conformal radiation therapy [10]. Using the SEER-Medicare linked database, Sher et al found that patients living in a census tract with higher median income were significantly more likely to be treated with intensity-modulated radiation therapy [11].…”

Proton Therapy in the Treatment of Head and Neck Cancer

“…A larger dosimetric advantage with proton therapy use is appreciable in the setting of ipsilateral treatment targets, such as salivary tumors or early tonsillar tumors. 6 In a study by Romesser et al, 7 41 patients who underwent ipsilateral RT for major salivary gland cancer or cutaneous squamous cell carcinoma were examined, 56% treated with IMRT and 44% with proton beam RT (PBRT The two groups, however, were not well balanced as higher risk histologies were in the photon group and the dose delivered was equivalent. These results are encouraging and emphasize the need for more randomized trials in various head and neck subsites.…”

Critical Update on Malignant Salivary Gland Neoplasms

“…Most recently, proton beam radiotherapy (PBRT) has emerged as an attractive treatment modality in the management of salivary neoplasms. 27 Due to its unique physical properties of proton energy deposition, PBRT lowers normal tissue exposure without compromising target coverage, thereby improving the therapeutic ratio. 27 At this time, systemic chemotherapy has a limited role in the management of salivary malignancy.…”

“…27 Due to its unique physical properties of proton energy deposition, PBRT lowers normal tissue exposure without compromising target coverage, thereby improving the therapeutic ratio. 27 At this time, systemic chemotherapy has a limited role in the management of salivary malignancy. Clinical trials exploring the role of chemotherapy in the management of salivary gland carcinoma failed to show survival benefit.…”