The long-term survival of a thymic carcinoma patient treated with S-1: a case report and literature review

Salvage Chemotherapy in Patients with Previously Treated Thymic Carcinoma

Thymic carcinoma is a rare neoplasm, and it is difficult to achieve complete remission with systemic chemotherapy. In advanced or recurrent thymic carcinoma, platinum-based chemotherapy is chosen as the first-line setting; however, it remains unclear which regimen is better to improve its outcome. It remains unknown whether salvage chemotherapy should be administered to patients with platinum-based chemotherapy-refractory thymic carcinoma. Currently, several clinical studies have investigated the efficacy of second-line settings for advanced thymic carcinoma. As cytotoxic agents, S-1, amrubicin, pemetrexed, docetaxel, paclitaxel, and gemcitabine have been reported as prospective phase II studies or retrospective studies. The overall response rates (ORRs) of S-1, amrubicin, and pemetrexed were 25-50%, 11-44.4%, and 9-10%, respectively. Molecular targeting drugs, such as sunitinib, everolimus, and lenvatinib, also provide clinical effectiveness with tolerability after the failure of platinum-based regimens. Based on the results of the prospective phase II study, the ORR, median progression-free survival, and median overall survival were 16.6% and 5.6 months, respectively, in everolimus, 26% and 7.2 months, respectively, in sunitinib, and 38% and 9.3 months, respectively, in lenvatinib. Although it is difficult to compare each study, lenvatinib appears to be better in increasing efficacy as a second-line setting. However, each study had a small sample size, which may have biased the results of their studies. Further investigation is warranted to elucidate the therapeutic significance of salvage chemotherapy in advanced thymic carcinoma in a large-scale study.

Elevated serum CYFRA 21-1 level as a diagnostic marker for thymic carcinoma

Background

No useful tumor markers have been identified for the diagnosis of thymic carcinomas. Serum cytokeratin 19 fragment, measured using the CYFRA 21‐1 immunoassay, is used as a tumor marker for squamous cell carcinomas in various malignant tumors. Here, we evaluated the value of CYFRA 21‐1 in diagnosing thymic carcinoma.

Methods

We retrospectively reviewed 94 patients with pathological diagnoses of thymic carcinoma or thymoma (32 and 62 patients, respectively) who were referred to our departments between January 2000 and March 2019. Primary outcomes included tumor marker levels and their diagnostic accuracy.

Results

Patients with thymic carcinoma were significantly more likely to be male (thymic carcinoma, 68.8%; thymoma, 40.3%; p = 0.02), have an advanced TNM stage (p < 0.01), and a significantly higher CYFRA 21‐1 level than those with thymoma (thymic carcinoma: median = 4.2 ng/ml; interquartile range [IQR] = 2.1–6.1 ng/ml vs. thymoma: median = 1.2 ng/ml; IQR = 0.9–1.7 ng/ml; p < 0.01). Receiver operating characteristic curves demonstrated that the area under the curve for CYFRA 21‐1 to distinguish thymic carcinoma from thymoma was 0.86 (95% confidence interval [CI]: 0.74–0.93; cutoff = 2.7 ng/ml; sensitivity = 68.8%; specificity = 95.2%). Multivariable analysis demonstrated that CYFRA 21‐1 (odds ratio = 25.6; 95% CI: 4.6–141.6; p < 0.01) was an independent predictor for thymic carcinoma after adjusting for TNM stage.

Conclusions

Serum CYFRA 21‐1 level may help in diagnosing thymic carcinoma.

Dramatic Response of S-1 Administration to Chemorefractory Advanced Thymic Cancer

Thymic cancer (TC) is a rare malignancy in thoracic tumors, and there has been no standard therapeutics for advanced or relapsed patients. The clinical significance of second-line or beyond chemotherapy for platinum refractory advanced TC remains unclear. Here, we present the experience of a patient with TC showing a complete response to S-1 as third-line chemotherapy. A 54-year-old female with TC was treated with carboplatin plus paclitaxel and thoracic radiotherapy as first-line chemoradiotherapy and amrubicin as second-line chemotherapy. After 3 cycles of amrubicin administration, the metastatic hepatic lesions revealed a markedly progressive disease. A single agent of S-1 was administered as sequencing chemotherapy. After 2 cycles of S-1, the patient achieved a complete remission of multiple metastatic sites. There was evidence of immunohistochemical staining of a low thymidylate synthase (TS) expression. The expression of TS may be closely associated with the efficacy of S-1 in patients with TC.