Proton therapy for thymic malignancies: multi-institutional patterns-of-care and early clinical outcomes from the proton collaborative group and the university of Florida prospective registries

Authors

  • Catherine E. Mercado University of Florida Health Proton Therapy Institute, Jacksonville, FL, USA
  • William F. Hartsell Northwestern Chicago Proton Center, Warrenville, IL, USA
  • Charles B. Simone II Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
  • Henry K. Tsai New Jersey Procure Proton Therapy Center, Oklahoma City, OK, USA
  • Carlos E. Vargas Mayo Clinic, Scottsdale, AZ, USA
  • He J. Zhu University of Florida Health Proton Therapy Institute, Jacksonville, FL, USA
  • Randal H. Henderson University of Florida Health Proton Therapy Institute, Jacksonville, FL, USA
  • Jing Zeng Department of Radiation Oncology, University of Washington, Seattle, WA, USA
  • Gary L. Larson Oklahoma City Procure Proton Therapy Center, Oklahoma City, OK, USA
  • Bradford S. Hoppe University of Florida Health Proton Therapy Institute, Jacksonville, FL, USA

DOI:

https://doi.org/10.1080/0284186X.2019.1575981

Abstract

Objective: Thymic malignancies (TM) are rare tumors with long-term survivorship, causing concerns for radiotherapy-related late side effects. Proton therapy (PT) reduces the radiation dose to organs at risk, potentially decreasing long-term toxicities while preserving disease control. We report patterns-of-care and early clinical outcomes after PT for thymoma and thymic carcinoma.

Methods: Between January 2008 and March 2017, 30 patients with TMs enrolled on one of two IRB-approved prospective protocols and received postoperative or definitive PT. Clinical outcomes, pathology, treatment dose, toxicities, and follow-up information were analyzed.

Results: Twenty-two thymoma patients with a median age of 52.1 years (range, 23–72) received a median RT dose of 54 Gy (RBE) (range, 45–70) either postoperatively (91%) or definitively (9%); 23% received adjuvant chemotherapy. Among eight thymic carcinoma patients, the median age was 65.5 years (range, 38-88) and median RT dose was 60 Gy (RBE) (range, 42–70) delivered postoperatively (75%) or definitively (25%); 50% received chemotherapy.

Median follow-up for all patients was 13 months (range, 2–59 months). Five patients relapsed, one locally (3%). Three patients died of disease progression, including two thymomas and one thymic carcinoma patient; a fourth died of intercurrent disease. One patient with thymic carcinoma and 1 with thymoma are alive with disease. No patients treated with PT for their initial disease (de novo) experienced grade ≥3 toxicities. The most common grade 2 toxicities were dermatitis (37%), cough (13%), and esophagitis (10%).

Conclusion: Adjuvant and definitive PT are being used in the treatment of TMs. Early results of the largest such cohort reported to date demonstrates an acceptable rate of recurrence with a favorable toxicity profile. Longer follow-up and a larger patient cohort are needed to confirm these findings.

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Published

2019-07-03

How to Cite

Mercado, C. E. ., Hartsell, W. F. ., Simone II, C. B. ., Tsai, H. K. ., Vargas, C. E. ., Zhu, H. J. ., … Hoppe, B. S. . (2019). Proton therapy for thymic malignancies: multi-institutional patterns-of-care and early clinical outcomes from the proton collaborative group and the university of Florida prospective registries. Acta Oncologica, 58(7), 1036–1040. https://doi.org/10.1080/0284186X.2019.1575981

Issue

Vol. 58 No. 7 (2019): Acta Oncologica

Section

Articles