Immunohistochemical detection of p53 and bcl-2 in colorectal carcinoma: noevidence for prognostic significance

To evaluate the prognostic significance of immunohistochemically detected p 53 and Bcl-2 proteins in colorectal cancer, tissue sections from 238 paraff in-embedded colorectal carcinomas were immunostained for p53 (MAb DO-7 and CM-1 antiserum) and Bcl-2 (MAb Bcl-2:124). Staining patterns were assessed semiquantitatively and correlated with each other and with sex, age, tumour site, Dukes' classification, tumour differentiation, mucinous characterist ics, lymphocyte and eosinophilic granulocyte infiltration, and patient surv ival. In our series, 35% of carcinomas showed no nuclear staining and 34% ( DO-7) to 40% (CM-1) showed staining in over 30% of tumour cell nuclei. A ma jority of carcinomas that had been immunostained with CM-1 showed cytoplasm ic staining, but this was not observed with DO-7. With respect to Bcl-2, 51 % of tumours were completely negative, 32% displayed weak and 15% moderate staining; only 3% showed strong positive staining. No evidence was found fo r reciprocity between Bcl-2 expression and nuclear p53 accumulation. From 1 3 cases containing tumour-associated adenoma, four were Bcl-2 negative in p remalignant and malignant cells, in another four cases these cells showed s imilar staining intensities and in the remaining cases only the malignant c olorectal cells were Bcl-2 negative. Therefore, our data indicate that Bcl- 2 is dispensable in the progression towards carcinoma. Except for an associ ation between nuclear p53 accumulation and mucinous tumours (P = 0.01), no significant correlation was found between the clinicopathological parameter s mentioned above and immunostaining pattern of (nuclear or cytoplasmic) p5 3 or Bcl-2.