Prognostic value of methylator phenotype in stage III colon cancer treated with oxaliplatin-based adjuvant chemotherapy

Abstract Purpose: There are conflicting results concerning the prognostic value of the CpG island methylator phenotype (CIMP) in patients with nonmetastatic colon cancer. We studied this phenotype in stage III colon cancer characterized for mismatch repair (MMR), RAS, and BRAF status, and treated with adjuvant FOLFOX-based regimen. Experimental Design: Tumor samples of 1,907 patients enrolled in the PETACC-8 adjuvant phase III trial were analyzed. The method used was methylation-specific PCR, where CIMP+ status was defined by methylation of at least 3 of 5 following genes: IGF2, CACNA1G, NEUROG1, SOCS1, and RUNX3. Association between CIMP status and overall survival (OS), disease-free survi…