Histopathological tumor regression or ypN: Which better predicts survival of patients who received neoadjuvant chemotherapy and surgery for non-type 4 locally advanced gastric cancer?

Abstract

114 Background: Histopathological tumor regression with < 10% residual tumor is a globally accepted prognostic factor in gastric cancer patients who received neoadjuvant chemotherapy (NAC) and curative surgery, however, impact of ypN remains unclear. Methods: Previously, Japan Clinical Oncology Group (JCOG) had conducted 3 phase II trials to evaluate NAC with irinotecan/CDDP (JCOG0001) and S-1/CDDP (JCOG0405) for extensive nodal disease, and with S-1/CDDP (JCOG0210) for large type 3 and type 4 (linitis plastica) disease. Prognostic factors, including ypN and histopathological tumor regression with < 10% residual tumor, were analyzed in patients with curative resection excluding type 4 advanced gastric cancer in these trials by univariable and multivariable analyses using the Cox proportional hazards model. Results: Among 85 patients, 5-year OS was 46.0% (95% CI, 35.0-56.4). Median OS was not reached in patients with < 10% residual tumor (n = 26), whereas that was 2.7 years (95% CI, 1.4-4.5) in patients with > 10% residual tumor (n = 59) (p = 0.008). Median OS was not reached in patients with ypN0-1 (n = 25), whereas that was 2.6 years (95% CI, 1.5-4.0) in patients with ypN2-3 (n = 60) (p = 0.003). On multivariable analysis, only ypN2-3 was an independent predictor of OS (hazard ratio, 3.67; 95% CI, 1.55 to 8.69), whereas < 10% residual tumor was not (hazard ratio, 2.24; 95% CI, 0.98 to 5.10). Conclusions: It is suggested that ypN may have greater impact on the survival than histopathological tumor regression in patients who received NAC and surgery for AGC.