Loss of Bcl-2 expression in colon cancer: A prognostic factor for recurrence in stage II colon cancer

Abstract 

Aims

To evaluate the prognostic value of immunohistochemical expression of Bcl-2 in colon cancers.

Patients and methods

Two hundred and twenty-six resected and paraffin-embedded colon carcinomas were analysed by immunostaining using monoclonal antibodies for Bcl-2. We evaluated whether the Bcl-2 staining patterns, semi-quantitatively assessed, could be correlated with the pTNM stage, size and tumour circumference, differentiation, appearance, vascular invasion, perineural invasion, colloid component, margins, involvement of adjacent structures, stromal appearance, flow cytometry and the S-phase.

Results

Eighty patients (36%) were considered Bcl-2 positive. The extent of Bcl-2 expression by tumour cells decreased significantly with respect to increasing tumour size (P=0.042), the extension of parietal invasion pT (P=0.007), the invasive nature of the tumour (P=0.024), and extent of the circumference (P=0.024). In a multivariate analysis, Bcl-2 expression does not appear as an independent prognosis factor in the overall population as in the 166 patients with optimal resection. Of the 59 stage II patients, using univariate analysis, Bcl-2 appears to be predictive of relapse-free survival (P=0.025) but not of overall survival (P=0.09).

Conclusion

The loss of Bcl-2 expression appears to be correlated with increase in number of relapses in the stage II colon cancers and could be a potential useful additional histo-prognostic marker in therapy decision making. Bcl-2 immunodetection seems to be associated with slower local tumour growth.

Keywords: Colon cancer, Prognosis, Bcl-2, Immunohistochemistry, Tumour relapse