Correlation of Ki-67 Proliferating Index with Histological Types and Characterization of Mucin in Colorectal Carcinoma

Background: Colorectal carcinoma is a major cause of cancer associated with a high rate of morbidity and mortality in the western world. One of the pathologic features considered to be important for prognosis is mucin production. Many authors confirmed that colon carcinomas with high mucin content tend to recur locally and carry a poor prognosis. Aim: Correlation of Ki-67 proliferating index with different type of colorectal carcinoma as well as characterization of mucin. Method: This cross sectional study was conducted at Sir Salimullah Medical College, Department of pathology from July 2014 to June 2016. Ninety eight patients with colorectal carcinoma was enrolled in this study who underwent surgical resection of colon, adenocarcinomas. For histological classification we used the WHO recommendation (2000) and to be more accurate we sub-classified mucinous adenocarcinomas by morphometrical analysis in three categories: pure mucinous, with extracellular mucin more than 80% of the tumoral volume; mixed type, with 50–80% extracellular mucin; and mixed type with less than 50% extracellular mucin and their correlation with Ki-67 proliferating index . For histochemical investigation, we used stains such as: D- PAS and Alcian Blue. A technique of manual tissue array was employed to see Ki-67 expression by IHC method. Ki-67 is a proliferation associated nuclear antigen which can be recognized by MIB-1 monoclonal antibody. Result: It was observed that Ki-67 labeling index was high in nonmucinous tumor compared to mucinous adenocarcinoma and signet ring cell carcinoma which is statistically significant (P80%) and mixed type (50-80%). The result was statistically significant (p<0.05). Correlation of Ki-67 proliferating index with histologic type as well as mucin characterization and thereby provide information to clinician to better understanding of the treatment as well as prognosis.