Testing for mutations of the ataxia telangiectasia gene in radiosensitive breast cancer patients.

Background And Purpose: To determine if clinical radiosensitivity in breast cancer patients is related to mutations of the ataxia telangiectasia gene (ATM).

Materials And Methods: Fifteen patients who had developed a severe late reaction to a standard radiotherapy schedule were examined for evidence of increased in vitro radiosensitivity using the MTT assay. Mutation analysis was performed using a protein truncation assay.

Results: No mutations were detected in the 15 patients despite evidence of increased in vitro radiosensitivity.

Conclusions: Testing for the ATM gene is unlikely to be useful for predicting clinical response to radiotherapy in breast cancer patients.