Successful Chemotherapy with Carboplatin and S-1 for Thymic Carcinoma: A Case Report
A 74-year-old female was diagnosed with thymic carcinoma in October 2012. Magnetic resonance imaging (MRI) of the chest revealed a large anterior mediastinal mass, pleural dissemination, and pericardial effusion (fig. ). Immediate pericardiocentesis improved her cardiopulmonary distress. A CT-guided percutaneous biopsy of the anterior mediastinal mass was done and small tissue fragments were obtained. Histologically, the tumor was composed of epithelioid cells with high cellularity, which had nuclear atypia and eosinophilic cytoplasm in fibrotic stroma (fig. ). Lymphoid cell infiltration was not evident in the tumor. Immunohistochemically, tumor cells were positive for epithelial markers such as AE1/3 and CK5/6. In addition, CD5 (fig. ) and CD117 (fig. ) were also detected in tumor cells. Neuroendocrine markers including chromogranin A and synaptophysin were negative. The tumor cells showed a high MIB-1 labeling index (approximately 30%). These findings were consistent with thymic carcinoma. According to the Masaoka classification, the patient had unresectable, locally advanced disease (IVa). In consideration of the complication of the pericardial effusion and the fact that the patient had adequate organ function, we initially treated her with carboplatin plus paclitaxel. However, an allergic reaction to paclitaxel occurred. In November 2012, the patient provided written informed consent before treatment and she was started on carboplatin (AUC, 5) plus oral S-1 (40 mg/m2 twice per day) on days 1–14 as second-line chemotherapy in cycles which were repeated every 3 or 4 weeks. After 2 cycles of this regimen, MRI of the chest revealed a 32% decrease in the diameter of the anterior mediastinal tumor and a reduction of the pericardial effusion, indicating a partial response based on the RECIST criteria (fig. ). The partial response was confirmed after 4 cycles of this regimen (fig. ). Hematologic toxicity consisted of grade 3 neutropenia and grade 1 thrombocytopenia, and nonhematologic toxicity consisted of grade 2 nausea, grade 2 anorexia, and grade 1 fatigue. No dose reduction was necessary. Since the completion of treatment with carboplatin plus oral S-1, the patient has remained well, and no disease progression has been observed up until the time of writing this case report (September 2013).