A histopathological assessment of the response of rectal adenocarcinoma to combination chemo-radiotherapy: relationship to apoptotic activity, p53 and bcl-2 expression

Aims To investigate the use of pre-operative chemo-irradiation in downstaging 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 apoptosis, mitosis, p53 and bcl-2 protein expression in pre-treatment biopsies. Results All tumours were resectable following chemo-irradiation. Six cancers showed complete regression with no viable tumour in the resection specimen. A significant correlation was found between spontaneous tumour apoptosis and tumour regression. Conclusions Our results suggest that in rectal cancer the apoptotic rate in untreated tumour tissue may predict sensitivity to radiation and cytotoxic agents. No relationship was found between regression and mitotic rate, p53 or bcl-2 expression.