P16 and p27 Immunohistochemical Expression in Colorectal Cancer: Analysis of 128 Patients

P16 and p27 are inhibiting proteins of cyclin-dependent kinases (CDKIs) that act in the restriction points of the cellular cycle, and it avoids its progression to DNA verification and repair by the cellular apparatus. This way, there should be, physiologically, an inverse relation between the expression of these proteins and cellular proliferation. However, what is really observed are changeable amounts of p27 in normal and tumor tissues. P16 participation in tumorigenesis is controversial. The expression of p16 and p27 as a prognostic factor in colorectal cancer (CRC) patients is controversial. Objetive: To establish a correlation between p16 and p27 immunohistochemical expressions with clinical and anatomopathological variable from patients with CRC. Material and methods: descriptive and retrospective study, with 128 CRC patients, treated surgically between 2000 and 2004, with available material for immunohistochemical analysis through standardized methods. The association between categorical variables was done using Chi-square, Pearson or Fisher?s Exact tests, and the continuous variables were analyzed by t-Student. Global survival and disease-free period were calculated according to Kaplan-Meier method and the associations through log-rank test. Results: The average follow-up time of patients was 35 months. Positivity of p16 was detected in 100% of cases. Negativity of p27 in 6.3% (n=8) of cases, with a significant association (p30.05) between p27 negative and tumors located in right colon (62.5%, n=5) and mucinous (62.5%, n=5). The average global survival was 54.8 months, and the significant clinical and pathological variables associated to survival were: better for curative surgeries; better for early stages; better for well-differentiated tumors; worse for cases with sanguineous or vascular lymphatic invasion; worse for perineural invasion. Conclusions: p27 negative is more frequent in right colon...

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

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...