Mutations of the p53 gene have been found in 380 of the 768 tumors (49.5%) included in the eight largest published series of colorectal cancer. Most point mutations of p53 change the conformation of the gene, and by stabilizing it make it detectable by immunohistochemistry. However, studies using both tests for p53 mutations and immunohistochemical methods found that the results of these two approaches were concordant in only 68% of cases. Conflicting data have been reported regarding the prognostic significance of positive p53 staining. Presence of a mutation is generally believed to indicate a poor prognosis.