Confirmation that chromosome 18q allelic loss in colon cancer is a prognostic indicator

Purpose: Recent studies suggest that allelic loss of sequences from the long arm of chromosome 18 may be a useful prognostic indicator in colorectal cancer. The aim of the present study was to confirm whether 18q loss of heterozygosity (LOH) is of prognostic value in patients with colon cancer. Methods: Genomic DNA was prepared from archival tumor and corresponding normal tissue specimens from 151 patients who had undergone potentially curative surgery for adenocarcinoma of the colon. Polymerase chain reaction (PCR) was used to assess allelic loss of five chromosome 18q microsatellite markers in the tumors. The relationship between allelic loss and disease-free and disease-specific survival was investigated. Results: LOH was detected in 67 of 126 tumors. Chromosome 18q allelic loss was a negative prognostic indicator of both disease-free (relative risk [RR], 1.65; P = .01) and disease-specific survival (RR, 2.0; P = .003). 189 loss was also associated with significantly reduced disease-free and disease-specific survival in patients with stage II (P = .05 and P = .0156) and III (P = .038 and P = .032) disease. Conclusion: Chromosome 189 allelic loss is a prognostic marker in colorectal cancers. Chromosome 18 LOH studies may be useful in identifying patients with stage II disease who are at high risk for recurrence, and as such might benefit from adjuvant chemotherapy. (C) 1998 by American Society of Clinical Oncology.