2855 - Prospective Study on Head and Neck Stereotactic Body Radiotherapy: A Tolerance Analysis

10:45am - 12:00pm PT

Hall F

Screen: 17

POSTER

Presenter(s)

Stephan Tran, MD, BS, MBS - Sunnybrook Odette Cancer Centre, Toronto, ON

S. Tran¹, M. Galapin¹, L. Chin¹, A. Eskander², A. Bayley¹, I. Poon¹, and I. Karam¹; ¹University of Toronto - Sunnybrook Odette Cancer Centre, Toronto, ON, Canada, ²Department of Otolaryngology - Head and Neck Surgery, Sunnybrook Health Sciences Centre, Toronto, ON, Canada

Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) to the head and neck (HN) has been used as a treatment option in patients deemed medically unsuitable for radical treatment. This study reports on the acute and subacute toxicities of patients prospectively treated with primary HN SBRT at a tertiary high-volume institution.

Materials/Methods: From 2020 to 2024, patients treated with previously unirradiated SBRT to the HN region were enrolled in a prospective, single institutional study. All patients received a dose of 3500-5000cGy in 5 fractions delivered twice weekly to the gross target volume (GTV). Acute toxicities were graded according to the physician-reported Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Data was collected at baseline prior to HN SBRT, mid-RT, end of RT, and 1 and 3 months after RT completion. Patients who did not complete the prescribed treatment were excluded. Adverse events (AEs) grade = 3 were presented overall and by target site. A total of 54 patients were accrued. Of those, 6 were lost to follow up/withdrawn or passed away at 1 month and an additional 12 at month 3. Those who passed away died from non-RT related reasons.

Results: Patient target volumes were primary HN mucosal [n = 6], HN primary nodal/parotid [n = 15], cutaneous [n = 12], distant metastatic lesions [n = 21]. Additional nodal SBRT was also delivered in 2 patients in the HN mucosal and 2 patients in the cutaneous group. Grade = 3 SBRT related AEs within 3 months from the start of SBRT treatment were reported in 9 (16.7%) patients. The grade = 3 AEs occurred in 5 skin patients, 3 oral cavity patients and 1 parotid patient. Of these patients, grade 3 pain occurred in 1 skin patient (cheek) and 1 oral cavity patient (oral tongue and ipsilateral level I and II lymph nodes). Grade 3 acute dermatitis in 4 skin patients (post-auricular, pre-auricular, cheek x2) and 1 parotid patient. Grade 3 mucositis in 1 skin (cheek) and 2 oral cavity patients (oral tongue, buccal mucosa). Grade 3 AEs were experienced by 4 patients at 1 month who experienced pain [n = 1] and acute dermatitis [n=3]. At 3 months, 1 patient experienced grade 3 acute dermatitis. No grade 4 or 5 toxicity was observed.

Conclusion: In conclusion, HN SBRT is a safe and well tolerated treatment modality for patients with HN cancer or distant metastatic cancer to the HN region showing very low acute and subacute toxicity rates. Most grade 3 AEs resolved by 3 months, if they occurred, and no patient experienced grade 4 or 5 toxicity. Other long-term outcomes, including Quality of Life Questionnaires, will be reported in future publications.