Adjuvant Reirradiation With Proton Therapy in Head and Neck Squamous Cell Carcinoma

Abstract

BackgroundFor patients with head and neck squamous cell carcinoma (HNSCC), locoregional failure and second primary tumors are common indications for adjuvant re-irradiation (re-RT). Given an absence of clear consensus on the role of adjuvant re-RT, we sought to assess histopathologic risk factors of HNSCC patients and their resulting outcomes after adjuvant re-RT with proton therapy. Methods and MaterialsWe conducted a retrospective analysis of HNSCC patients who underwent salvage surgery at our institution followed by adjuvant re-RT with proton therapy over 1.5 years. All included patients received prior radiotherapy. The Kaplan-Meier method was used to evaluate locoregional recurrence-free survival (RFS) and overall survival (OS). ResultsThe cohort included 22 patients, with disease subsites including oropharynx, oral cavity, hypopharynx, larynx, and nasopharynx. Depending on adverse pathologic features, adjuvant re-RT to 66Gy (32% of cohort) or 60Gy (68%), with (59%) or without (41%) concurrent systemic therapy was administered. The majority (86%) completed re-RT with no reported treatment delay; 3 patients experienced grade >=3 acute Common Terminology Criteria for Adverse Events (CTCAE) toxicity and no patient required enteral feeding tube placement during re-RT. Median follow-up was 21.0 months (IQR 11.7-25.2 months). Five patients had biopsy-proven disease recurrences a median of 5.9 months (IQR 3.8-9.7 months) after re-RT. Locoregional RFS was 95.2%, 70.2%, 64.8% at 6, 12, and 24 months, respectively. OS was 100%, 79.2%, and 79.2% at 6, 12, and 24 months, respectively. Four patients had osteoradionecrosis on imaging a median of 13.2 months (IQR 8.7-17.4 months) after re-RT, with two requiring surgical intervention. ConclusionsAdjuvant re-RT for HNSCC patients was well-tolerated and offered reasonable local control in this high risk cohort, but appears to be associated with a risk of osteoradionecrosis. Further study and longer follow-up could help define optimal patient management in this patient population.