Main Session
Sep
28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology
2713 - Clinical Implementation of a Low-Dose Hyper-Radiosensitivity Priming Strategy In Re-Irradiation for Recurrent or Second Primary Head and Neck Cancer: Early Feasibility Experience
Presenter(s)
Yu-Wei Lin, MD, PhD, MS - Kaohsiung Veterans General Hospital, Kaohsiung, Kaohsiung
S. W. Chiang, and Y. W. Lin; Department of Radiation Oncology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
Purpose/Objective(s):
Re-irradiation (re-RT) for recurrent or second primary head and neck cancer (HNC) remains clinically challenging due to cumulative normal tissue constraints and a limited therapeutic index. Low-dose hyper-radiosensitivity (HRS), observed in preclinical systems at doses <0.5 Gy, has been hypothesized to enhance tumor cell kill prior to full activation of DNA damage repair pathways. However, clinical data supporting implementation of HRS-guided priming strategies in head and neck re-RT are limited. We report our initial institutional experience evaluating the feasibility and early safety of a low-dose HRS priming approach in this setting.Materials/Methods:
We retrospectively reviewed patients with recurrent or second primary HNC previously treated with radiotherapy (RT) who underwent re-RT incorporating a low-dose HRS priming strategy. The regimen consisted of a 0.25 Gy priming dose immediately preceding each therapeutic fraction of 1.80–2.75 Gy, delivered over 10–20 fractions. Prior radiation dose, interval between treatment courses, and cumulative equivalent dose in 2 Gy fractions (EQD2) were calculated using the linear-quadratic model, with composite plan summation performed for cumulative dose assessment to organs at risk. Acute toxicities were graded according to CTCAE v5.0. Patient demographics, tumor characteristics, dosimetric parameters, and early toxicity outcomes were analyzed descriptively.Results:
Between January 2025 and December 2025, 13 patients undergoing 15 re-RT courses met inclusion criteria. The median interval between previous RT and re-RT was 12 months. All treatment courses were completed without interruption. With a median follow-up of 2 months, no = Grade 3 acute toxicities were observed. No early vascular complications or unexpected adverse events were identified. Oncologic outcomes, including local control and survival, were not assessable given the limited follow-up duration.Conclusion:
In this early retrospective experience, implementation of a low-dose HRS priming strategy in head and neck re-RT was technically feasible and did not demonstrate unexpected acute toxicity. These preliminary safety observations support further prospective investigation and extended follow-up to define durability of response and late effect profiles. Longer follow-up and validation studies are warranted to establish both safety and potential efficacy.