A case of signet-ring cell carcinoma of the lung responding to S-1 as the third therapeutic regimen

Background. Signet-ring cell carcinoma of the lung is a rare tumor with poor prognosis. No large-scale clinical trials have been published examining the effect of anticancer drugs. Case. A 38-year-old man was admitted to our hospital with an abnormal shadow in the right lung on a chest radiograph detected on a medical checkup. His right upper lobe was collapsed, and bronchial washing using a fiberoptic bronchoscope yielded a cytological diagnosis of adenocarcinoma. The right middle and lower lobes showed shadows suggestive of carcinomatous lymphangiosis, and metastatic lesions were identified in the cerebellar vermis. Because systemic anticancer chemotherapy consisting of docetaxel and cisplatin, and irinotecan and cisplatin did not have any effect S-1 was given as a third therapeutic regimen. A retroperitoneal metastatic mass adjacent to the left iliopsoas muscle and a right adrenal gland metastatic mass were transiently, but markedly reduced in size. Primary lung adenocarcinoma with signet-ring cell components was identified on autopsy. Conclusion. The effectiveness of S-1 should be considered which is an effective anticancer drug for gastric cancer, in the treatment of primary signet-ring cell carcinoma of the lung.