Radiosensitivity of normal tissues in ataxia-telangiectasia heterozygotes

Purpose: Approximately 5% of cancer patients given radiation therapy exhibit severe injuries to the noncancerous tissue in the radiation field. Striking clinical sensitivity to ionizing radiation has been observed frequently in ataxia-telangiectasia (A-T) homozygotes, This study was undertaken to test the hypothesis that heterozygous carriers of a mutated gene for A-T may represent a substantial proportion of all patients who suffer severe radiation toxicity, Methods: The medical records of all A-T heterozygotes treated with radiation therapy for breast or prostate cancer were compiled from an ongoing study of mortality and cancer incidence in A-T families. Diagnostic, treatment, and follow-up records were reviewed. Acute and long-term radiation complications were scored according to Radiation Therapy and Oncology Group criteria. Results: There were no instances of soft tissue necrosis or other apparent serious injuries to normal tissues of two A-T heterozygotes with prostate carcinoma and 11 with breast carcinoma who received moderate-to-high doses of conventionally fractionated radiation therapy by megavoltage techniques. Conclusion: There is no evidence that abnormal clinical radiosensitivity occurs in A-T heterozygotes receiving conventionally fractionated radiation therapy for breast or prostate cancer. (C) 1998 Elsevier Science Inc.