Loss of Bcl-2 expression correlates with tumour recurrence incolorectal cancer

Aims—To investigate the associationbetween immunohistochemical expression of Bcl-2 and p53 in colorectalcancer and tumour recurrence following surgery.
Methods—Sixty six cases of Dukes'B colorectal carcinoma were studied. All tumours were moderatelydifferentiated and were shown to be histologically clear of theresection margins. Immunohistochemistry was performed on formalin fixedparaffin wax embedded tissue using monoclonal antibodies for p53 andBcl-2. The Bcl-2 staining was assessed separately for relativeintensity of staining and percentage of positive tumour cells and givena final score which combined the two factors. The p53 staining wasassessed on number of positive tumour cells only. The patterns ofimmunostaining of those cases in which there had been tumour recurrencewere compared with those cases in which there was no tumour recurrence (controls).
Results—A statistically significantinverse association was found between Bcl-2 score and tumour recurrence(median Bcl-2 score of 6 (interquartile range (IQR) 2-9) in patientswith recurrent disease; median Bcl-2 score of 8 (IQR 6-10) in thosewithout recurrence; p=0.03). When examined separately, both theintensity of expression and percentage of positive tumour cells weresignificantly associated with tumour recurrence (p=0.04 in each case).There was no association between p53 staining and tumour recurrence.
Conclusion—Results suggest that,when controlled for differentiation, Bcl-2 expression is a prognosticmarker and may be useful as an adjunctive test in clinical decision making.

Keywords:colorectal cancer; tumour recurrence; Bcl-2; p53; Jass grouping