The postoperative lean body mass loss at one month leads to a poor survival in patients with locally advanced gastric cancer.

: We previously demonstrated that a loss of lean body mass loss at one month after gastrectomy was an independent risk factor for the continuation of adjuvant chemotherapy with S-1. However, it is unclear whether or not lean body mass loss after gastrectomy leads to a poor survival through poor compliance to adjuvant chemotherapy with S-1. : The recurrence free survival (RFS) overall survival (OS) and were examined in 115 patients who underwent curative gastrectomy and were pathologically diagnosed with stage II or III gastric cancer and who received postoperative adjuvant chemotherapy with S-1 between May 2011 and September 2016. : The median follow-up period was 40.6 months. The RFS rates at 5 years after surgery were 57.8% in the lean body mass loss ≥5% group and 73.5% in the lean body mass loss <5% group. The univariate and multivariate analyses for the disease free survival (RFS) demonstrated that a lean body mass loss >5% was a significant risk factor. The OS rates at 5 years after surgery were 72.0% in the lean body mass loss ≥5% group and 77.3% in the lean body mass loss <5% group. The OS was slightly worse in the lean body mass loss ≥5% group than in the lean body mass loss <5% group (p=0.2062). : The lean body mass loss at one month, which is closely associated with poor S-1 compliance, was an important risk factor for the RFS. A prospective cohort study is necessary to confirm whether or not the lean body mass loss affects the gastric cancer survival.