The association between inflammatory infiltration, fibrosis, necrosis and mucinous content in rectal cancers, and their relationship to preoperative radiotherapy (RT) clinicopathological and biological factors (p53, apoptosis and Cox-2) is not fully characterised. We analysed these histopathological parameters and their relationships in rectal cancer patients who participated in a clinical trial of preoperative RT. One hundred and forty-eight preoperative biopsies and 153 surgically resected tumours were examined. Of the surgical specimens, 81 had surgery alone and 72 received RT before surgery. A higher grade of inflammatory infiltration was related to favourable survival in the whole group of patients (p=0.004, for multivariate analysis p=0.01) as well as in the subgroups of patients with (p=0.04) or without RT (p=0.01). After RT, tumours showed a decreased infiltration (p=0.0003) and increased necrosis (p=0.006), strong necrosis was related to favourable survival (p=0.046). Necrosis (p=0.054) and fibrosis (p=0.06) tended to be increased in p53-negative tumours after RT. Inflammatory infiltration was a strong prognostic factor in rectal cancer patients, regardless of RT. RT tended to induce necrosis and fibrosis in p53-negative tumours.

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