Investigation of the biological significance of p53 tumor suppressor gene and Ki-67 in colorectal carcinoma resected from Saudi patients: An immunohistochemical analysis

ABSTRACT

p53 protein accumulation has been shown to be an unfavorable prognostic parameter in many human cancers, but findings in colorectal carcinoma [CRC] are equivocal. The objective of this study is to evaluate the value of p53 and Ki-67 as prognostic markers in patients with colorectal carcinoma. We conducted a retrospective analysis on 56 colorectal cancer specimens resected at King Abdulaziz university hospital, Jeddah, Saudi Arabia [40 cases of left colon and 16 from right colon]. Immunohistochemistry [IHC] was performed on formalin fixed paraffin embedded tissue using the avidin-biotin peroxidase complex method. Antibodies to p53 [DO7] and Ki-67 were used. This was correlated with the following clinicopathologic parameters patient sex, age and survival; pathological stage, and grade of the tumors. Among the 56 cases of colorectal cancer [male/female=1.3; mean age 54.9 years, range 30-80 years], 85.7% [n=48] of tumors were positive for p13 IHC. Ki-67 was positive in 94% [n=53]. The p53 positivity in different stages was as follows [2/2 stage A, 23/28 stage B, 15/18 stage C and 8/8 stage D]. The positivity of p53 according to tumor differentiation was as follows [well differentiated 6/6, moderately differentiated 38/45, poorly differentiated 4/5]. P53 was positive in 34/40 of left colon [including rectosigmoid] and in 14/16 of right colon carcinoma. Imunoreactivity for p53 was seen in adenomatous epithelium only in 8/22 cases. Although p53 and Ki-67 expression expresse4 strongly in cancer compared to normal tissue [p<0.05], there was no relation with survival, grade or Dukes' stage of the tumor. P53 cannot be considered as independent prognostic marker in colorectal carcinoma