[Determination of proliferative activity using Ki67 and expression of p53 in colorectal cancer]

Classically, neoplasia has been considered a disturbance in the regulation of proliferation. In the search of a prognostic discriminant, the distribution of Ki67 as a marker of cell proliferation and the expression of p53 was studied in patients with colorectal cancer, to see whether this marker correlate with clinicopathological aspects.

Formalin-fixed paraffin-embedded tissues from 38 surgically resected adenocarcinomas of colon and rectal (5 Dukes A, 15 B and 18 C) were examined for p53 and Ki67 reactivity by immunohistochemistry (Dako). Nuclear staining of 5% of the cells was the criterion for a positive p53 reaction. For the study of Ki67 10 or more fields were chosen until 1000 nuclei per specimen were counted. The Ki67 labelling indices was determined by the number of positive nuclei/1000 cells. Correlation was done with the Dukes stage, grade of differentiation and percentual of recurrence.

The mean Ki67 labelling indices was 40. The p53 was positive in 79% of the patients. The mean of Ki67-Li was higher in the positive p53 patients. However we did not lymphatic find differences between Ki67 or p53 expression and sex, age, Dukes stage, grade of differentiation, neural, venous or lymphatic invasion or recurrence.

Ki67 and p53 could not be correlated to clinical and pathologic parameters in this study and was of limited use as a prognostic discriminant. The positive p53 cancers have more proliferative activity detected by a higher index of Ki67.