ASTRO 2020: Locoregional Failure Patterns With IMRT for Anaplastic Thyroid Cancer
Posted: Tuesday, November 10, 2020
Julianna K. Bronk, MD, PhD, of The University of Texas MD Anderson Cancer Center, Houston, and colleagues conducted an analysis to investigate the patterns of locoregional failure and patient outcomes after intensity-modulated radiation therapy (IMRT) in those with unresectable anaplastic thyroid cancer. The results, which were presented during the 2020 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 3980), may inform target volume delineation and treatment strategies.
The analysis focused on 30 patients with unresectable stage IVA/B or IVC anaplastic thyroid cancer who received therapeutic dose intensity-modulated radiation therapy. Locoregional failures were classified using spatial and dosimetric criteria: central high dose (type A); peripheral high dose (type B); central elective dose (type C); peripheral elective dose (type D); and extraneous dose (type E).
Locoregional and distant failure occurred in 57% and 80% of patients, respectively. The investigators identified 35 recurrent gross tumor volumes. The median duration of locoregional failure-free survival was 8.4 months. Dose fractionation did not seem to predict locoregional failure-free survival (P = .7). The duration of locoregional failure-free survival did not appear to differ between patients treated with a single dose or multiple dose levels (P = .7).
The majority of locoregional failures occurred in patients who received type A (71%) and type B (5.7%) dose volumes. The investigators reported two, one, and five recurrences in patients treated with types C, D, and E dose volumes, respectively. The mean high-dose target volume was 217 cc in patients with locoregional failure and 192 cc in those without (P = .6). The median duration of overall survival was 6.7 months from the end of treatment. The median duration of overall survival was shorter in patients who had stage IVA/B tumors with locoregional failure than in those without (11 vs. 15 months, respectively; P = .7).
Disclosure: For full disclosures of the study authors, visit www.redjournal.org.