ATM expression in rectal cancers with or without preoperative radiotherapy.

Patients with ATM (Ataxia-Telangiectasia mutated) mutation show increased sensitivity to radiation and have a higher risk of developing malignancies. The present study aimed to investigate whether ATM expression was related to radiotherapy, and clinicopathological and biological variables in rectal cancers. ATM expression was immunohistochemically examined in 78 rectal cancers from patients who participated in a Swedish rectal cancer trial of preoperative radiotherapy. Of 78 patients, 44 underwent surgery alone, and 34 underwent both preoperative radiotherapy and surgery. Fifty-eight cases had normal rectal mucosa adjacent to the tumour. The results showed that, compared to normal mucosa, tumours had less nuclear (p=0.03) but more cytoplasmic expression of ATM (p=0.004). In tumours, less expression of ATM, either in the nucleus (p=0.07) or in the cytoplasm (p=0.02 for staining intensity, and p=0.07 for staining percentage), tended to be correlated with male patients. Also, ATM expression was not related to radiotherapy or other clinicopathological and biological variables (p>0.05). In conclusion, the pattern of ATM expression was changed from normal mucosa to tumour. Less expression of ATM may be related to males.