A Case of Rhabdomyolysis Believed to Be Caused by TS-1 during Postoperative Adjuvant Chemotherapy for Gastric Cancer

Abstract

Rhabdomyolysis is a reported adverse event of TS-1. The case of a patient with rhabdomyolysis believed to have been caused by TS-1 is presented. A 74-year-old man had previously taken oral medication for diabetes and hypertension, but he was not currently taking any such medication. He had undergone total gastrectomy, D2 lymph node dissection, and Roux-en-Y reconstruction for gastric cancer 18 months previously. The pathological diagnosis was T3 (SS) N0(0/52) H0 P0 CY0 M0 Stage IIA. From postoperative Day 42, postoperative adjuvant chemotherapy was started with TS-1 on a schedule of 2 weeks' oral administration and 1 week drug holiday. The patient was able to tolerate this regimen with no obvious adverse events. In Month 15 of this treatment, which had been continued at the patient's request, he became aware of generalized loss of muscle strength and weakness in the legs. He became unable to walk and was examined on Day 2 after the symptoms appeared. Abnormal blood test results were WBC 23,600/μl, LDH 544 U/l, CK 20,052 U/l, and CRP 26.7 mg/dl, and blood and urinary myoglobin were both elevated, at 360 ng/ml and 2,800 ng/ml, respectively. Rhabdomyolysis was diagnosed on the basis of these results. The symptoms improved after the patient was admitted for intravenous therapy, and he was discharged improved on Day 11. This case of rhabdomyolysis during treatment with oral TS-1 is reported, together with a discussion of the literature.