Skeletal Muscle Mass Before Second-line Chemotherapy Correlates With Subsequent Prognosis and Rate of Late-line Chemotherapy in Patients With Unresectable Gastric Cancer

Abstract

Background/Aim: Chemotherapy is the standard treatment for patients with unresectable gastric cancer (UGC); however, the survival outcomes are poor. This study investigated the predictive values of skeletal muscle mass (SMM) index (SMI) before second-line chemotherapy and the survival outcomes of patients with UGC. Patients and Methods: A total of 79 patients diagnosed with UGC at our hospital who received at least second-line palliative chemotherapy were included. The cross-sectional SMM at the third lumbar vertebra was obtained before second-line chemotherapy. SMI was defined as the muscle area normalized by height squared (m²), and SMI before second-line chemotherapy was defined as 2^ndSMI. Results: Using 2^ndSMI for men and women (35.4 and 31.7 cm²/m², respectively) as the cutoff value, patients were divided into high (2^ndSMI^High; n=54) and low (2^ndSMI^Low; n=25) 2^ndSMI groups. The number of patients receiving fourth-line chemotherapy was significantly higher in the 2^ndSMI^High group than in the 2^ndSMI^Low group (p=0.039). The overall survival time after the start of second-line chemotherapy was significantly higher in the 2^ndSMI^High group than in the 2^ndSMI^Low group (p=0.008). The incidence of grade 3 or 4 side effects was significantly higher in the 2^ndSMI^Low than in the 2^ndSMI^High group (p=0.028). The multivariate analysis identified 2^ndSMI as independent prognostic factor after the start of second-line chemotherapy. Conclusion: The 2^ndSMI^Low group had a significantly worse prognosis and significantly less conversion to fourth-line chemotherapy than the 2^ndSMI^High group. Moreover, 2^ndSMI^Low was associated with grade 3 or 4 side effects of second-line chemotherapy.