Phase II study of S‐1 plus cisplatin with concurrent radiotherapy for locally advanced thymic carcinoma: Results of the LOGIK1605/JART‐1501 study

Background Combination chemotherapy is used to treat advanced thymic carcinoma; however, the effects are insufficient. Methods Previously untreated patients with unresectable locally advanced thymic carcinoma received two cycles of 80 mg/m2/day S‐1 orally on days 1–14 plus 60 mg/m2/day cisplatin intravenously on day 1, and concurrent radiotherapy (60 Gy). Results Three patients were enrolled into the study. Toxicity and survival were assessable in all patients, but the treatment response was only assessable in one patient. The study was terminated because of poor case recruitment. The patients' characteristics were as follows: male/female = 2/1; PS 0/1 = 2/1; median age (range) = 59 (55–72); and stage III/IV = 2/1. The patient in which the treatment response was assessed exhibited SD (response rate: 0%). In both nonevaluable cases, the second course of chemotherapy was judged to be post‐protocol treatment because it was delayed by ≥14 days, but a CR and PR were achieved after the end of the study, respectively. G4 leukopenia/neutropenia and G3 febrile neutropenia occurred in one patient each (33%). The median time to tumor progression was 17.6 months, and the 1‐, 2‐, 3‐, and 4‐year survival rates were 67, 33, 33, and 33%, respectively. The median overall survival time was not reached, and the 1‐, 2‐, 3‐, and 4‐year survival rates were 100, 67, 67, and 67%, respectively. Conclusions Although it was difficult to recruit patients, there was a long‐term survivor >4 years who appeared to have achieved a CR, indicating that such chemoradiotherapy may be effective against locally advanced thymic carcinoma. A prospective phase II trial was performed. Although it was difficult to recruit patients, there was a long‐term survivor >4 years.