p53 and p21 Immunohistochemistry in Colorectal Cancer: Clinical and Pathological Correlation in 128 Cases

ABSTRACT

Mutations of tumoral suppressor TP53 gene are present in 75% of colorectal cancer (CRC) cases. Immunohistochemistry isa method capable of demonstrating the abnormal accumulation of p53 protein in the cell. Some studies associate p53immunohistochemical positivity and a worse prognosis, while others do not confirm this finding. There are controversiesregarding the prognostic value of p53 in CRC. The same doubts apply to p21 protein, activated by p53, which is the mainresponsible for stopping the cell cycle (checkpoints), both for repair or apoptosis purposes. Objective: The objective of thisstudy is to correlate p53 and p21 immunohistochemical expression both with clinical and anatomopathological variables andwith survival rates of patients with CRC. Materials and Methods: This is a descriptive and retrospective study having asresearch subjects 128 patients affected by CRC and treated surgically from 2000 to 2004, with available surgical specimensfor immunohistochemical analysis using standardized methods. The association among categorical variables was done byPearson chi-square or Fisher exact tests, and the continuous variables were analyzed by t-Student test. Overall survival anddisease-free period rates had been calculated according to Kaplan-Meier method and the associations by log-rank test. Results:Follow-up average time was 35 months. p53 and p21 alterations had been detected, respectively, in 67.2% and 27. 3% ofcases, with a significant association (p<0.05) between p53 and tumors located in rectum (76.0%) and left colon (70.7%), andbetween p21 and right colon (43.2%). p21 positive expression was related to CRC diagnostic at an older median age. Overallsurvival was 54 months, and the significant clinical and pathological related variables were the following better for curativesurgeries; better for precocious stages; better for well-differentiated tumors; worse for cases with sanguineous or lymphatic...