ESTRO 2024 - Abstract Book

S1244

Clinical - Head & neck

ESTRO 2024

Purpose/Objective:

The "Quad Shot" regimen is an altered fraction cyclical palliative radiotherapy (RT) course of 44.4 Gy in 12 fractions over 8 weeks. It has demonstrated effective local control for head and neck cancer (HNC) patients with minimal toxicities in the RTOG 8502 and an Australian phase II studies (1,2). However, this treatment remains underutilized due to concerns regarding toxicities, patient convenience, and efficacy given the split-course nature of the regimen. This study presents the results of a mildly accelerated Quad Shot regimen in a community hospital setting, highlighting its feasibility, effectiveness, and safety.

Material/Methods:

A retrospective analysis was performed for all biopsy-proven HNC cases receiving Quad Shot RT between 2015 and 2022 in a single-institution community center. Mildly accelerated Quad Shot RT over 6 weeks delivered 44.4 Gy in 12 fractions (2 fractions/day over two consecutive days, every 3-weeks). Patients were planned with thermoplastic masks and fusion with any available diagnostic imaging. PTV margins were a 5 mm expansion on GTV defined with PET, CT or MRI fusion. There were no CTV expansions, and elective lymph nodes were not treated. Treatments were planned with Volumetric Modulated Arc Therapy techniques primarily using the Raystation planning system (Raysearch Laboratories, Sweden). Patients received no concurrent systemic agents. We evaluated overall survival (OS), disease-free survival (DFS), and toxicity rates.

Results:

The study included 31 patients (61% men, 39% women) with a median age of 80 years (range 52-97) and a median ECOG of 1 (range 0-3). Median follow-up was 14.7 months. Primary cancer sites comprised 55% oropharynx, 26% larynx/hypopharynx, 6% oral cavity, 6% salivary glands, and 6% other sites. P16 status was negative in 29%, positive in 42%, and unknown or not applicable in 29%. Staging (AJCC 8th Ed) demonstrated 55% of patients with cT3-4 disease, cN2-3 39%, and cM1 accounted for 9%. A total of 27 patients (87%) completed the treatment. 23 of these patients successfully finished their treatment within the 6-week period. Additionally, three patients completed the regimen in 7 weeks, and one patient in 8 weeks. Grade 1 and 2 acute toxicities were observed in 88% and 33% of patients, respectively. Grade 3 toxicities were observed in 2 patients, and both patients did not complete treatment. No grade 4 or 5 toxicities occurred. Post-treatment response, assessed at a median of 1.33 months, demonstrated an overall response rate of 84%. This included a complete response in 42% of patients and a partial response in another 42%. For the patients who did not respond to RT, one patient demonstrated progressive disease during treatment, while four patients had stable disease. Mean OS was 17.6 months (median 15.6). Mean DFS was 10.4 months (median 6.7). In-field recurrence occurred in 12 patients, regional recurrence in 13 and distant failure in 2.

Conclusion:

Quad Shot palliative RT for HNC patients provided excellent response rates and DFS with a favorable toxicity profile. Furthermore, our study underscores the feasibility of this approach within the community hospital setting. OS was favorable compared to previous series, possibly suggesting differences in patient selection or histological