The role of salvage radiotherapy in recurrent thymoma
- Author:
Andrew Jihoon YANG
1
;
Seo Hee CHOI
;
Hwa Kyung BYUN
;
Hyun Ju KIM
;
Chang Geol LEE
;
Jaeho CHO
Author Information
- Publication Type:Original Article
- Keywords: Thymoma; Radiotherapy; Survival; Recurrence
- MeSH: Disease-Free Survival; Follow-Up Studies; Humans; Lung; Multivariate Analysis; Pleura; Prescriptions; Radiotherapy; Recurrence; Thymoma; Treatment Failure
- From:Radiation Oncology Journal 2019;37(3):193-200
- CountryRepublic of Korea
- Language:English
- Abstract: PURPOSE: To explore the role of salvage radiotherapy (RT) for recurrent thymoma as an alternative to surgery. MATERIALS AND METHODS: Between 2007 and 2015, 47 patients who received salvage RT for recurrent thymoma at Yonsei Cancer Center were included in this study. Recurrent sites included initial tumor bed (n = 4), pleura (n = 19), lung parenchyma (n = 10), distant (n = 9), and multiple regions (n = 5). Three-dimensional conformal and intensity-modulated RT were used in 29 and 18 patients, respectively. Median prescribed dose to gross tumor was 52 Gy (range, 30 to 70 Gy), with equivalent doses in 2-Gy fractions (EQD₂). We investigated overall survival (OS), progression-free survival (PFS), and patterns of failure. Local failure after salvage RT was defined as recurrence at the target volume receiving >50% of the prescription dose. RESULTS: Median follow-up time was 83 months (range, 8 to 299 months). Five-year OS and PFS were 70% and 22%, respectively. The overall response rate was 97.9%; complete response, 34%; partial response, 44.7%; and stable disease, 19.1%. In multivariate analysis, histologic type and salvage RT dose (≥52 Gy, EQD₂) were significantly associated with OS. The high dose group (≥52 Gy, EQD₂) had significantly better outcomes than the low dose group (5-year OS: 80% vs. 59%, p = 0.046; 5-year PFS: 30% vs. 14%, p=0.002). Treatment failure occurred in 34 patients; out-of-field failure was dominant (intra-thoracic recurrence 35.3%; extrathoracic recurrence 11.8%), while local failure rate was 5.8%. CONCLUSION: Salvage RT for recurrent thymoma using high doses and advanced precision techniques produced favorable outcomes, providing evidence that recurrent thymoma is radiosensitive.
