(S001) Tumor Control and Toxicity Outcomes for Head and Neck Cancer Patients Re-Treated With Intensity-Modulated Radiation Therapy (IMRT)-A Fifteen-Year Experience

Vinita Takiar, MD, PhD, Dominic Ma, BS, Adam S. Garden, MD, Beth M. Beadle, MD, PhD, Clifton D. Fuller, MD, PhD, Gary B. Gunn, MD, William H. Morrison, MD, David I. Rosenthal, MD, Jack Phan, MD, PhD; UT MD Anderson Cancer Center

PURPOSE AND OBJECTIVES: The probability of locoregional failure after definitive treatment for cancers in the head and neck (H&N) area approaches 50%, with 80% of such failures occurring within previously high-dose–treated radiation volumes, within 2 years of treatment. Historically, H&N cancers arising in previously irradiated volumes were rarely re-treated with radiotherapy due to toxicity concerns. With improved precision in planning and delivery, re-irradiation is now used with greater frequency. Here, we review and analyze our 15-year institutional experience using only intensity-modulated radiation therapy (IMRT) to treat previously irradiated H&N carcinoma.

MATERIALS AND METHODS: We retrospectively reviewed the records of 227 patients who were re-irradiated to the H&N using IMRT between 1999 and 2014. Radiation-related acute and late toxicity, including events requiring hospitalization or urgent intervention and death were recorded. Outcome variables included gender, age, surgery, chemotherapy, radiotherapy dose, radiotherapy volume, and time between initial irradiation and re-irradiation. 

RESULTS: A total of 206 patients (91%) were treated with definitive intent. Of them, 104 patients (50%) underwent salvage resection and 136 patients (66%) received chemotherapy. Median follow-up after re-irradiation for definitely treated patients was 24.7 months. The 5-year rates of locoregional control, progression-free survival, and overall survival for definitively treated patients were 54%, 25%, and 39%, respectively. Actuarial rates of grade ≥ 3 toxicity were 32% at 2 years and 48% at 5 years, with dysphagia or odynophagia requiring feeding tube placement representing the most common toxicity of grade ≥ 3. On multivariate analysis, concurrent chemotherapy and retreatment site influenced tumor control, whereas response to induction chemotherapy and initial disease site influenced survival. High-dose clinical tumor volume (CTV1) > 50 cc and concurrent chemotherapy were significantly associated with increased grade ≥ 3 toxicity. Notably, patients who were treated to a CTV1 < 25 cc experienced no grade ≥ 3 toxicity.

CONCLUSIONS: Re-irradiation for H&N cancers with IMRT and concurrent chemotherapy results in promising local control and survival outcomes in selected patients. Treatment-related toxicity continues to be significant despite improvements in systemic therapy and radiation dose conformality, warranting careful patient selection and target volume delineation.

Proceedings of the 97th Annual Meeting of the American Radium Society - americanradiumsociety.org