New Approaches to Assessing and Treating Early-Stage Colon and Rectal Cancers: Cooperative Group Strategies for Assessing Optimal Approaches in Early-Stage Disease

Abstract

The U.S. Gastrointestinal Intergroup (GI Intergroup), including the National Cancer Institute of Canada, has created a portfolio of clinical trials for patients with stage II and III colon and rectal cancer, integrating therapeutic strategies from recent advanced disease trials. Fluoropyrimidine-based combination therapy for metastatic disease, with either irinotecan or oxaliplatin plus bevacizumab, has resulted in significant improvement in response and disease-free and overall survival. Cetuximab and irinotecan have produced intriguing response and progression-free survival data from randomized phase II trials. Although patients with stage II and III rectal cancer are uniformly included in individual clinical trials, the GI Intergroup conducts separate trials in patients with stage II and III colon cancer, with the exception of the National Surgical Adjuvant Breast and Bowel Project (NSABP), which continues to merge both stages in their statistical designs. The U.S. chemotherapy platform for adjuvant therapy clinical trials is based on the positive adjuvant data from NSABP C-07 [FLOX with bolus 5-fluorouracil (5-FU)] and the MOSAIC trial (FOLFOX with infusional 5-FU). Three irinotecan-based adjuvant trials (one U.S. and two European) did not reach designated statistical end points. In addition, the GI Intergroup has consistently integrated molecular biological and other laboratory projects as important components of past and current trials. NSABP has recently completed accrual of patients to C-08, which is evaluating FOLFOX with or without bevacizumab in stage II/III colon cancer. E5202, the largest U.S. stage II colon cancer trial, determines patient risk by the initial evaluation of tumor 18q loss of heterozygosity and microsatellite instability status. Low-risk patients are observed, whereas high-risk patients are randomized to FOLFOX with or without bevacizumab. N0147 evaluates FOLFOX with or without cetuximab in patients with stage III disease. Two large rectal cancer trials have begun to accrue patients. NSABP R-04 compares neoadjuvant radiation with either continuous infusion 5-FU with or without oxaliplatin versus capecitabine with or without oxaliplatin. E5204 is the adjuvant comparison of FOLFOX with or without bevacizumab and is also available to NSABP R-04 patients.