Oral 2.03: S-1 salvage treatment for chemorefractory stage IV thymic carcinoma: a report of 19 cases

Background: It remains challenging to deal with progression disease of thymic carcinoma after previous systemic chemotherapy. By now, there are a few case reports from Japanese authors about the effects of S-1 on such patients. In this study, we reported the clinical outcome of S-1 as a salvage chemotherapy in a larger number of patients.

Methods: Patients, pathologically diagnosed as thymic carcinoma, were enrolled in this study when confirmed with extensive lesions. All patients had to receive at least one regimen of chemotherapy and showed disease progression before considering the choice of S-1. The following eligibility criteria should be met: PS score ≤2; leukocyte count ≥3.0×10⁹/L; platelet count ≥80×10⁹/L. The capsules were taken orally twice daily at a dose of 60–70mg/m² per day for 2 weeks, followed by 1-week drug-free interval. Each cycle contains 4-week drug application and two-week interval. The cycles would be repeated unless disease progressed or intolerable adverse effect was confirmed.

Results: From January 2011 to April 2015, totally 19 patients (male: female =9:10) have been included in this study with a median age of 56 [27–75]. The majority of pathological subtype is squamous cell carcinoma (15 cases). There are also two undifferentiated carcinoma, one lymphoepithelioma-like carcinoma and one high grade neuroendocrine carcinoma. Eight patients had metastasis in lung, four in liver, three in lymph nodes and two in brain. Another four patients failed in pleural dissemination. Before S-1, all patients received first-line chemotherapy, 14 out of 19 patients received second-line chemotherapy, and three patients received third-line chemotherapy. The average cycles applied in all patients are 3.4, ranging from 1 to 12. The overall response status are partial response 3 (16%), stable disease 13 (68%) and progression disease 3 (16%). The median progression free survival is 5 months [0–15]. Among the three patients with progression disease, two have brain metastasis, and the other one is neuroendocrine carcinoma. The main toxicity over grade 2 are appetite loss in 9 (47.3%), platelet count dropping in 4 (21%) and hemoglobin leveling down in 2 (10%). Most of the side effects are moderate and do not lead to drug suspension.

Conclusions: S-1 could be used as an effective salvage chemotherapy for extensive thymic carcinoma to relieve symptoms and to extend survival span with low toxicity. But it seems that patients with brain metastasis or those classified as neuroendocrine carcinoma could not benefit from this regimen.

Keywords: S-1; chemotherapy; thymic carcinoma