Intensity modulated radiotherapy in locally advanced thyroid cancer: Outcomes of a sequential phase I dose-escalation study

Publication date: Available online 7 March 2018
Source:Radiotherapy and Oncology
Author(s): K.P. Rooney, A.B. Miah, S.A. Bhide, M.T. Guerrero-Urbano, M.T. Sharabiani, K.L. Newbold, L. Grove, K.J. Harrington, C.M. Nutting
Background and purposeTo determine the safety and tolerability of dose-escalation using modestly accelerated IMRT in high-risk locally advanced thyroid cancer requiring post-operative radiotherapy, and to report preliminary data on efficacy.Materials and methodsA sequential Phase I dose-escalation design was used. Dose level one (DL1) received 58.8 Gy/28F to the post-operative bed and 50 Gy/28F to elective nodes. DL2 received 66.6 Gy/30F to the thyroid bed, 60 Gy/30F to post-operative nodal levels and 54 Gy/30F to elective nodal levels. Acute (NCICTCv.2.0) and late toxicities (RTOG and modified LENTSOM) were recorded. The primary endpoint was the number of patients with ≥Grade 3 (G3) toxicity at 12 months post-treatment.ResultsFifteen patients were recruited to DL1 and twenty-nine to DL2. At 12 months ≥G3 toxicities were 8.3% in both DL1 and DL2. At 60 months, ≥G3 toxicity was reported in 3 (33%) patients in DL1 and 1 (7%) in DL2. One patient in DL2 died at 24 months from radiation-induced toxicity. Time to relapse and overall survival rates were higher in DL2, but this was not statistically significant.Dose-escalation using this accelerated regimen can be safely performed with a toxicity profile similar to reported series using conventional doses.



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