Evaluation of prognostic factors in gene expression and clinicopathologic characteristics in patients with adjuvant chemotherapy for advanced gastric cancer.
61 Background: We reported TS expression is an independent prognostic factor in patients with gastric cancer who received postoperative adjuvant chemotherapy with S-1 at 2010 ASCO GI (abstract 32). These pharmacogenomic finding will help for choosing chemotherapeutic agents for personalized therapy in the future. Our aim was to indicate association of TS expression with clinicopathological characteristics in the same patient population. Methods: 39 patients with stage II or III advanced gastric cancer who underwent gastrectomy were analyzed. These patients received adjuvant chemotherapy with S-1 after surgery. Formalin-fixed, paraffin-embedded tumor tissues were dissected by the laser-captured microdissection technique and analyzed for target gene expressions using a quantitative real-time PCR. Results: There were no significant differences between stage II and III in TS gene expressions. TS expression (low ≤ 0.72, high > 0.72) and histological type (intestinal and diffuse) are evaluated for PFS and OS. Patients were classified as Group I (n = 5); low TS and intestinal type, Group II (n = 14); low TS and diffuse type, Group III (n = 13); high TS and diffuse type and Group IV (n = 7); high TS and intestinal type. There were significant differences between these four groups (Kaplan-Meier survival analysis, log-rank test, PFS: p = 0.0112 OS: p = 0.0128). The survival curve showed longer survival both PFS and OS in Groups 1 > 2 > 3 > 4. In low TS situation (responders as Group I and II), there is a trend in patients with intestinal type had a longer survival compared to diffuse type (Group I > II). In high TS situation (non-responders as Group III and IV), the result are opposite, there is a trend in patients with diffuse type had a longer survival compared to Intestinal type (Group III > IV). Conclusions: These data suggest that TS gene expression levels may be molecular markers of prognostic factor for patients with adjuvant chemotherapy for resectable gastric cancer. S-1 might be effect different behavior by both histological type and TS expression. Prospective studies are needed to validate these preliminary findings. No significant financial relationships to disclose.