Intensity-modulated Radiotherapy plus Etoposide/Cisplatin for Patients with Limited Advanced Unresectable Thymic Epithelial Tumors: A Prospective Phase II Study

Abstract Introduction This prospective phase II study evaluated the efficacy and safety of intensity-modulated radiotherapy (IMRT) plus etoposide/cisplatin (EP) for patients with unresectable thymic epithelial tumors (TETs). Methods 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 radiotherapy, followed by two cycles after radiotherapy. The primary endpoint was the objective response rate (ORR). The secondary endpoints were the progression-free survival (PFS) rate, overall survival (OS) 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 ORR 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 PFS rates were 66.1%, 48.0%, and 29.5%, and the 1-, 2-, and 5-year OS rates were 91.0%, 76.2%, and 56.2%, respectively. The most common grade 3–4 adverse events were leukopenia (42.9%), and pulmonary fibrosis was also observed (5.3%). Conclusions As IMRT with EP is effective and safe for limited advanced unresectable TETs, it could be a suitable treatment option for such patients.