A randomized Phase II study of external beam reirradiation versus external beam reirradiation plus radiosurgery boost in recurrent nasopharyngeal carcinoma

Abstract

PURPOSE/OBJECTIVE(S): Stereotactic radiosurgery (SRS) has been employed in salvaging local failure of nasopharyngeal carcinoma (NPC), and excellent long-term control has been reported in patients with limited tumor extent and volume. Most patients with locally recurrent NPC have advanced disease and external beam reirradiation is often necessary to ensure adequate target coverage. Combining external beam reirradiation and SRS boost allows delivering of a high radiation dose to the target which may improve tumor control and outcome. MATERIALS/METHODS: We performed this phase II randomized study to compare the safety and efficacy of using SRS boost versus no boost after external beam reirradiation for locally recurrent NPC. Thirty-one patients were randomized, with 15 patients in the SRS boost arm. External beam reirradiation was performed using three-dimensional conformal technique or step-and-shoot intensity modulated radiotherapy. The median dose was 54 Gy in both arms. Patients randomized to SRS boost arm received single fraction of linac-based radiosurgery at 2 - 3 weeks after completion of radiotherapy, and the median dose was 11 Gy delivered to 80% isodose line. The primary endpoint was local control (LC), and secondary endpoints were overall survival (OS) and toxicity. RESULTS: The median follow-up was 19 months. Three-year LC rates were 58% in SRS boost arm and 36.8% in no boost arm, and 3-year OS rates were 40% in SRS boost arm and 37.5% in no boost arm. In patients treated for rT1 - 3 stage, 3-year LC rates were 83% in SRS boost arm and 42.9% in no boost arm. The corresponding figures in those treated for rT4 stage were 20% and 33.3%. Approximately 73.3% of patients in SRS boost arm and 62.5% of patients in no boost arm had late toxicity following treatment. Incidence of grade 3 late toxicities were 6.7% in SRS boost arm and 25% in no boost arm. CONCLUSIONS: External beam reirradiation followed by SRS boost is a feasible and well-tolerated regimen for locally recurrent NPC. Phase III randomized trial is warranted to define the role of adding SRS boost to external beam radiotherapy for locally recurrent NPC. Copyright © 2011 Published by Elsevier Inc.