The impact of dose modification or termination of S-1 as adjuvant therapy on survival of locally advanced gastric cancer underwent curative gastrectomy.

193Background: Adjuvant S-1 therapy for pStage II/III gastric cancer (GC) patients (pts) after curative resection is standard treatment in Japan, however, prognosis of pStage III is still poor. There are few reports investigating the association of treatment exposure with survival. Therefore, we investigated the impact of dose modification or termination of S-1 as adjuvant therapy on overall survival (OS). Methods: The data of locally advanced GC pts who underwent gastrectomy with D2 lymph-node dissection in Shizuoka Cancer Center between Jan 2007 and Aug 2013 were retrospectively collected. Inclusion criteria were as follows: age 20 to 80 years; ECOG PS 0 or 1; histologically proven adenocarcinoma; pStage III under TNM 7th edition; R0 resection; initiation of S-1 within 56 days after surgery. S-1 was administered for 4 weeks followed by a 2 weeks rest. We defined completion of planned S-1 therapy as continuation of S-1 one year after surgery. Results: One hundred and six pts satisfied inclusion criteria....