External beam radiation therapy for recurrent or residual thyroid cancer: What is the best treatment time and the best candidate for long‐term local disease control?
Lara Bessa Campelo Pinheiro Cavalcante, Natalia Treistman, Fabiola Maria Teresa Torres Gonzalez, Pollyanna Iemini Weyll Fernandes, Paulo Alonso Garcia Alves Junior, Fernanda Accioly Andrade, Elisa Napolitano Ferreira, Tarcisio Fontenele De Brito, Attilio Pane, Rossana Corbo, Felipe Erlich, Daniel Alves Bulzico, Fernanda Vaisman- Otorhinolaryngology
Abstract
Introduction
Cervical disease control might be challenging in advanced thyroid cancer (DTC). Indications for cervical external beam radiation therapy (EBRT) are controversial.
Purpose
To identify clinical and molecular factors associated with control of cervical disease with EBRT.
Methods
Retrospective evaluation and molecular analysis of the primary tumor DTC patients who underwent cervical EBRT between 1995 and 2022 was performed.
Results
Eighty adults, median age of 61 years, were included. T4 disease was present in 43.7%, lymph node involvement in 42.5%, and distant metastasis in 47.5%. Those with cervical progression were older (62.5 vs. 57.3, p = 0.04) with more nodes affected (12.1 vs. 2.8, p = 0.04) and had EBRT performed later following surgery (76.6 vs. 64 months, p = 0.05). EBRT associated with multikinase inhibitors showed longer overall survival than EBRT alone (64.3 vs. 37.9, p = 0.018) and better local disease control. Performing EBRT before radioiodine (RAI) was associated with longer cervical progression‐free survival (CPFS) than was RAI before (67.5 vs. 34.5, p < 0.01). EBRT ≥2 years after surgery was associated with worse CPFS (4.9 vs. 34, p = 0.04). The most common molecular alterations were ERBB2, BRAF, FAT1, RET and ROS1 and TERT mutation was predictive of worse disease control after EBRT (p = 0.04).
Conclusion
Younger patients, with fewer affected nodes and treated earlier after surgery had better cervical disease control. Combination of EBRT with MKI improved OS. TERT mutation might indicate worse responders to EBRT; however, further studies are necessary to clarify the role of molecular testing in selecting candidates for cervical EBRT.