Background: S-1 is an oral anticancer drug widely used in postoperative adjuvant therapy for patients in Japan with stage II/III gastric cancer. Candidates for more intense adjuvant treatments need to be identified, particularly among patients with stage III cancer.
Methods: Univariate and multivariate analyses were conducted for patients with stage II/III gastric cancer who underwent surgery and received S-1 postoperatively between 2000 and 2010.
Results: Factors indicating poor prognosis identified by univariate analysis include male sex (P = 0.022), age ≥67 years (P = 0.021), intestinal-type histology (P = 0.049), lymph node ratio ≥16.7 % (P < 0.0001), open surgery (P = 0.039), as well as the 13th JGCA stage (P < 0.0001) and the 14th JGCA/7th International Union Against Cancer (UICC) stage (P < 0.0001). Multivariate analysis revealed that lymph node ratio ≥16.7 % and intestinal-type histology were significant as predictors of prognosis, independent from the pathological stages. Based on these and other findings, stage IIIC cancer on the 14th JGCA/7th UICC stage system in combination with the lymph node ratio could identify patients with extremely high risk for recurrence
Conclusions: Our current findings suggest that lymph node ratio ≥16.7 % in combination with the new staging system could be a useful prognostic indicator in advanced gastric cancer. Because these high-risk patients cannot be identified preoperatively by any diagnostic tool, further improvement in postoperative adjuvant therapy is warranted.