Immunohistochemical Expression of P16ink4a in Colorectal Adenocarcinoma Compared to Adenomatous and Normal Tissue Samples: A Study on Southeast Iranian Samples

Abstract

Background: Colorectal cancer (CRC) is one of the most common neoplasms of the digestive system with high morbidity and mortality. Treatment of CRC in advanced metastatic stages is problematic. Thus, early diagnosis in primary stages using sensitive molecular markers seems to be necessary. Objectives: This study aimed at investigating the immunohistochemical expression of P16ink4a in CRC compared to adenomatous and normal colorectal tissue samples of a population from the southeast of Iran. Methods: This case-control study was conducted on 137 colorectal formalin fixed paraffin-embedded tissue blocks for P16ink4a a protein using Immunohistochemistry (IHC). The tissue blocks were categorized in 3 groups, including adenocarcinoma (n = 63), adenomatous (n = 38), and normal (n = 36). All tissue blocks were collected from the pathology department of Ali-Ebne-Abitaleb central and referral Hospital, Zahedan, Iran from 2010 to 2015. The sections were evaluated using semi-quantitative scoring. The P16ink4a expression was reported as negative and positive. Clinicopathological characteristics were also assessed. The data were analyzed by Kruskal-Wallis and Fisher exact tests. The significance level was considered as P < 0.05. Results: The expression of P16ink4a in adenocarcinoma, adenomatous, and normal colorectal tissues was 25.40%, 50.00%, and 69.50%, respectively. The P16ink4a expression was significantly higher in non-neoplastic tissues compared to the adenomatous and colorectal tissues (P < 0.001). There was a significant association between P16ink4a expression and differentiation grade (P < 0.001) and primary location of the tumor (P = 0.010). Conclusions: Considering the significant expression of P16ink4a in normal compared to adenomatous and cancerous samples, it seems that this biomarker could be used as a potential useful predictor for screening and diagnosis of CRC patients in early stages. Further researches should be conducted on this matter.