Intensity Modulated Radiation Therapy Plus Etoposide/Cisplatin for Patients With Limited Advanced Unresectable Thymic Epithelial Tumors: A Prospective Phase 2 Study.

PURPOSE:This prospective phase 2 study evaluated the efficacy and safety of intensity modulated radiation therapy plus etoposide/cisplatin (EP) for patients with unresectable thymic epithelial tumors (TETs). METHODS AND MATERIALS:Patients with limited advanced unresectable TETs whose lesions could be encompassed within radiation fields were enrolled in this study. Two cycles of EP (75 mg/m2 etoposide and 25 mg/m2 cisplatin on days 1-3 and days 29-31) were administered concurrently with radiation therapy, followed by 2 cycles after radiation therapy. The primary endpoint was the objective response rate. The secondary endpoints were the progression-free survival rate, overall survival rate, and incidence of adverse events. RESULTS:Fifty-six patients were enrolled between June 2011 and May 2018. Twenty-two and 34 patients had thymomas and thymic carcinomas, respectively. The median age was 52 (range, 21-76) years, and 30 patients (53.6%) were men. Eight patients (14.3%) had stage III tumors, 6 (10.7%) had stage IVA tumors, and 42 (75.0%) had stage IVB tumors. The objective response rate was 85.7% (95% confidence interval, 76.3%-95.2%). With a median follow-up of 46 (range, 7-101) months, the 1-, 2-, and 5-year progression-free survival rates were 66.1%, 48.0%, and 29.5%, and the 1-, 2-, and 5-year overall survival rates were 91.0%, 76.2%, and 56.2%, respectively. The most common grade 3 to 4 adverse event was leukopenia (42.9%). Pulmonary fibrosis was also observed (5.3%). CONCLUSIONS:Because intensity modulated radiation therapy with EP is effective and safe for limited advanced unresectable TETs, it could be a suitable treatment option for such patients.