Background: Allelic loss of chromosome 18q predicts a poor outcome in patients with stage II colorectal cancer. Although the specific gene inactivated by this allelic loss has not been elucidated, the DCC (deleted in colorectal cancer) gene is a candidate. We investigated whether the expression of the DCC protein in tumor cells is a prognostic marker in colorectal carcinoma.
Methods: The expression of DCC was evaluated immunohistochemically in 132 paraffin-embedded samples from patients with curatively resected stage II and III colorectal carcinomas. The Cox proportional-hazards model was used to adjust for covariates including age, sex, tumor site, degree of tumor differentiation, and use of adjuvant therapy.
Results: The expression of DCC was a strong positive predictive factor for survival in both stage II and stage III colorectal carcinomas. In patients with stage II disease whose tumors expressed DCC, the five-year survival rate was 94.3 percent, whereas in patients with DCC-negative tumors, the survival rate was 61.6 percent (P<0.001). In patients with stage III disease, the respective survival rates were 59.3 percent and 33.2 percent (P=0.03).
Conclusions: DCC is a prognostic marker in patients with stage II or stage III colorectal cancer. In stage II colorectal carcinomas, the absence of DCC identifies a subgroup of patients with lesions that behave like stage III cancers. These findings may thus have therapeutic implications in this group of patients.