OP064: Reirradiation of head and neck cancers with IMRT: Updated outcomes and analysis

Abstract

Purpose Head and neck (H&N) cancers arising in previously irradiated volumes were rarely treated with radiotherapy due to concerns of toxicity. With improved precision in planning and delivery, reirradiation has been increasingly used. We reviewed our institutional experience using IMRT in the management of previously irradiated H&N carcinoma. Materials and methods The records of 136 patients treated with IMRT reirradiation at U.T. M.D. Anderson Cancer Center for H&N cancer between 1999 and 2012 were retrospectively reviewed. Reirradiation was defined as any overlap between the two radiation treatment volumes. Severe toxicity related to reirradiation included events requiring hospitalization, urgent intervention, or death. Survival estimates were calculated using the Kaplan–Meier algorithm, excluding those patients treated with palliative intent. Results Thirty-three (24%) patients underwent surgical resection and 70 (51%) patients received chemotherapy. Twenty of these patients received radiation with palliative intent. Median time interval between initial radiation and reirradiation was 23 months. Median follow-up after reirradiation was 33 months. Median reirradiation dose was 60 Gy (range 15–70 Gy), while the median cumulative radiation dose was 120 Gy. The 2- and 5-year overall survival and locoregional control rates were 58% and 63%, and 39% and 51%, respectively. Re-treatment doses ⩾66 Gy trended towards improved LRC ( p = 0.14). Severe reirradiation related toxicity occurred in 35 patients (26%), including three treatment-related deaths. Severe toxicity did not correlate with total or re-treatment dose but was associated with retreatment volumes >150 cc. Conclusions IMRT yields promising local control and survival outcomes in select patients receiving reirradiation for H&N cancer. However, treatment related toxicity continues to be significant despite the increased conformality of IMRT over 3D conformal radiation. Alternative treatment strategies, including the possible use of stereotactic radiotherapy, to further improve conformality and thereby increase the therapeutic ratio, may be explored in the future.