Relative dose intensity and 1-year psoas muscle index reduction rate as prognostic factors in gastric cancer patients with postoperative adjuvant chemotherapy.

Abstract

Higher relative dose intensity (RDI) of chemotherapy improves the clinical outcomes of various cancers. The psoas muscle index (PMI) is related to sarcopenia, and patients with low PMI have worse prognoses. However, few studies have demonstrated its clinical relevance in gastric cancer. This retrospective study included 188 stage II/III gastric cancer patients who had undergone curative gastrectomy between January 2013 and March 2017, 124 of whom had received postoperative S-1 adjuvant chemotherapy. Per receiver operating characteristic analysis, patients were divided into high and low RDI groups, between which relapse-free survival differed marginally significantly and disease-specific survival differed significantly. In patients who received adjuvant chemotherapy, multivariate analysis found that high RDI and low PMI reduction rate 1 year after surgery were significantly associated with better relapse-free survival. Low RDI can be predicted by a combination of low preoperative PMI and non-distal gastrectomy, whereas high PMI reduction rate at 1 year can be affected by non-distal gastrectomy. High RDI with preserved psoas muscle up to 1 year after gastrectomy may be associated with prognoses in gastric cancer requiring postoperative adjuvant chemotherapy. Since RDI and PMI reduction rate can be predicted preoperatively, respectively, interventional consideration is possible for optimal adjuvant therapy in gastric cancer.