A Validation Study of Relationships Among Genomic Gene Expression Profile, Prognosis and Prediction of Adjuvant Chemotherapy Benefit With Capecitabine and Oxaliplatin in Gastric Cancer Stage II and III (6th AJCC) Patients After D2 Surgery (CLASSIC)

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.

Inclusion criteria

• aged 18 years or older
• histologically confirmed, American Joint Committee on Cancer/Union Internationale Contre le Cancer (6th edition) 2 stage II (T2N1, T1N2, T3N0), IIIA (T3N1, T2N2, T4N0), or IIIB (T3N2) gastric adenocarcinoma with no evidence of metastatic disease
• previous D2 surgery with achieved R0 resection
• Karnofsky performance status of >70%
• adequate renal function (creatinine clearance >50 mL/min or serum creatinine ≤1·5 times the upper limit of normal), hepatic function (total bilirubin ≤1·5 times the upper limit of normal, aspartate or alanine aminotransferase ≤2·5 times the upper limit of normal), and hematological function (absolute neutrophil count ≥1·5 × 109/L or platelet count ≥100 × 109/L)
• adequate hepatic function
• formalin-fixed paraffin-embedded (FFPE) tumor blocks, pathologic reports, and clinical information were all available.

Exclusion criteria

• chemotherapy, immunotherapy, or radiotherapy for GC prior to surgery
• no available FFPE tumor blocks
• insufficient RNA quality to be analyzed.