A HISTOPATHOLOGICAL ASSESSMENT OF THE RESPONSE OF RECTAL ADENOCARCINOMA TO COMBINATION CHEMORADIOTHERAPY - RELATIONSHIP TO APOPTOTIC ACTIVITY, P53 AND BCL-2 EXPRESSION

Aims, To investigate the use of pre-operative chemo-irradiation in dow nstaging advanced rectal cancer prior to surgical resection. Methods. We examined the pathological effects of chemo-irradiation on 24 rectal tumours and correlated the efficacy of treatment with the level of ap optosis, mitosis, p53 and bcl-2 protein expression in pre-treatment bi opsies. Results. All tumours were resectable following chemo-irradiati on. Six cancers showed complete regression with no viable tumour in th e resection specimen. A significant correlation was found between spon taneous tumour apoptosis and tumour regression. Conclusions. Our resul ts suggest that in rectal cancer the apoptotic rate in untreated tumou r tissue may predict sensitivity to radiation and cytotoxic agents. No relationship was found between regression and mitotic rate, p53 or bc l-2 expression.