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Worth Attention thymoma imrt phase-2

Hemithoracic radiotherapy after surgery achieved durable control in pleural thymoma

After surgery and 14 Gy hemithoracic radiotherapy, five-year progression-free survival was 50.8% with only one grade 3 pneumonitis.

RadOncToday · ·1 min read

KEY POINTS

  • This prospective phase II study enrolled patients with de novo or recurrent thymoma with pleural dissemination who could undergo macroscopic resection. 71 patients completed the protocol between April 2020 and December 2021; median age was 46 years, with 32 de novo and 39 recurrent cases.
  • After surgery, patients received IMRT to the entire ipsilateral hemithorax at 14 Gy in 14 fractions. Patients with a primary mediastinal tumor above T2 received an additional 30 Gy in 15 fractions to the mediastinal tumor bed; treatment generally began 4–6 weeks after surgery.
  • At a median follow-up of 57 months, median progression-free survival was 50 months. Progression-free survival was 68.9% at 3 years and 50.8% at 5 years, while five-year overall survival reached 98.6%.
  • The study specifically tracked failure within the treated pleural compartment. Freedom from recurrence inside the radiation field was 78.8% at 3 years and 66.5% at 5 years.
  • Overall, 34/71 patients (47.9%) developed progression: 24 developed pleural recurrence within the radiation field and 10 outside it. Despite the large treated volume, survival compared favorably descriptively with older surgery-based series, although no randomized comparison was performed.
  • Acute gastrointestinal toxicity was the main treatment burden. RT had to be temporarily suspended after 4–8 fractions in 5 patients because of gastrointestinal symptoms; four restarted after 7–10 days and one after 15 days. Myasthenia gravis worsened during treatment in 2 patients, both of whom ultimately completed RT.
  • Radiation pneumonitis occurred in 7/71 patients (9.9%): four grade 1, two grade 2 and one grade 3. Most other treatment-related toxicities, including nausea, vomiting, fatigue, leukopenia, cough and dyspnea, were mild.

CLINICAL TAKEAWAY

For carefully selected patients with resectable stage IVa thymoma and pleural dissemination, surgery followed by low-dose entire hemithoracic RT produced encouraging five-year pleural control with limited severe pulmonary toxicity. The absence of a randomized comparator means the regimen should be viewed as promising prospective evidence rather than a definitive standard.

SOURCE

International Journal of Radiation Oncology, Biology, Physics