The purpose of this study is to validate a pre-defined single-patient classifier algorithm for predicting prognosis and benefit from adjuvant chemotherapy for patients who underwent D2 gastrectomy for stage II and III gastric cancer. This algorithm classifies gastric cancer into five groups according to its molecular characteristics based on RNA expression levels. The prognosis and response from adjuvant chemotherapy will be different according to prognostic and predictive clusters respectively based on these groups, thus this algorithm can identify as patients which will have benefit from adjuvant chemotherapy or which will not. Consequently, this algorithm can be translated into clinical practice to help doctors who decide the necessity of adjuvant chemotherapy after D2 gastrectomy for patients who had diagnosed stage II and III gastric cancer.~The cohort for this validation study is from patients who were enrolled the CLASSIC (Capecitabine and oxaliplatin Adjuvant Study in Stomach Cancer) trial, a randomized, open-label, multicenter, parallel-group, phase 3 study which compared the effect of adjuvant capecitabine plus oxaliplatin (XELOX) after D2 gastrectomy with surgery alone strategy. This trial was conducted between June, 2006 and June, 2009. The patient were from both surgery alone arm and surgery plus adjuvant XELOX arm, and have tumor blocks available for RNA extraction.
The purpose of this study is to validate a pre-defined single-patient classifier algorithm for predicting prognosis and benefit from adjuvant chemotherapy for patients who underwent D2 gastrectomy for stage II and III gastric cancer. This algorithm classifies gastric cancer into five groups according to its molecular characteristics based on RNA expression levels. The prognosis and response from adjuvant chemotherapy will be different according to prognostic and predictive clusters respectively based on these groups, thus this algorithm can identify as patients which will have benefit from adjuvant chemotherapy or which will not. Consequently, this algorithm can be translated into clinical practice to help doctors who decide the necessity of adjuvant chemotherapy after D2 gastrectomy for patients who had diagnosed stage II and III gastric cancer.