Correlation between L3 skeletal muscle index and prognosis of patients with stage IV gastric cancer

Background: To explore the relationship between L3 skeletal muscle index (SMI) and the prognosis of patients with stage IV gastric cancer (GC). Methods: A total of 27 patients with stage IV GC requiring chemotherapy admitted to our hospital from 1 April 2015 to 20 May 2019 were selected as participants. The Kaplan-Meier method was used to describe the survival time of all participants. By evaluating the L3 plane CT images, the mass index (cm2/m2) of L3 skeletal muscle (including psoas major, erector spinae, quadratus psoas, transversus abdominis, external oblique abdominis, and internal oblique abdominis) was calculated to study the changes of L3 SMI during treatment and the correlation between L3 SMI and clinical features. The log-rank method was used to analyze the correlativity between the survival time of patients and their general data, L3 SMI, or other indicators. Results: The survival time of 27 patients with stage IV GC was 7.4-49.9 months, with a mean survival time of 19.72 months and a median survival time of 16.17 months. The 1-year survival rate was 77.78%, and the 3-year survival rate was 7.41%. During treatment, L3 SMI continued to decline in 20 of the 27 participants (74.07%). After the first chemotherapy, 17 participants (62.96%) met the criteria of sarcopenia syndrome, and after the fourth chemotherapy, 19 participants (70.37%) met the criteria of sarcopenia syndrome. The L3 SMI was shown to be significantly correlated with body mass index (BMI) and Onodera's prognostic nutritional index (OPNI) (both P 0.05), but not with age, gender, dietary intake, and primary site (all P 0.05). Log-rank test showed that there was a correlation between L3 SMI and survival time of patients (P<0.05). The average survival time of participants with sarcopenia syndrome (16.78 months) was significantly lower than that of those without sarcopenia syndrome (25.58 months) (P<0.05). Conclusions: There is a significant correlation between L3 SMI and survival time, and L3 SMI can be used as a potential index to evaluate the prognosis of patients with stage IV GC.