Postoperative weight loss leads to poor survival through poor S-1 efficacy in patients with stage II/III gastric cancer

Aims: We previously demonstrated that body weight loss (BWL) at one month after gastrectomy, a common finding after surgery for gastric cancer, was an independent risk factor for the continuation of adjuvant chemotherapy with S-1. However, it is unclear whether BWL after gastrectomy leads to poor survival through poor compliance to adjuvant chemotherapy with S-1. Methods: We conducted this follow-up study in the same cohort as our previous study. Overall survival (OS) and recurrence-free survival (RFS) were examined in 103 patients who underwent curative D2 surgery and were pathologically diagnosed with stage II or III gastric cancer, and who received postoperative adjuvant chemotherapy with S-1 between June 2002 and December 2011. Results: The median follow-up period was 64.3 months. The 5-year OS rate in the patients with a BWL of <15% was 59.9%, while that in the patients with a BWL of ≥15% was 36.4% (p = 0.004). Univariate and multivariate analyses for OS demonstrated that pathological T factor and BWL were significant risk factors. On the other hand, the 5-year RFS rate was 56.4% in the BWL <15% group and 36.4% in the BWL ≥15% group (p = 0.016), while univariate and multivariate analyses for RFS demonstrated that BWL was a marginally significant risk factor. Conclusions: Severe postoperative BWL, which is closely related with poor S-1 compliance, is an important risk factor for survival. It merits testing if preventing BWL improves survival of gastric cancer patients who receive S-1 adjuvant chemotherapy.