LETTERS: Outcomes of Adjuvant Radiation Therapy for Breast Cancer in Women With Ataxia-Telangiectasia Mutations 11/14/2001; Journal of the AMA To the Editor: Women who are carriers of single mutations in the ataxia-telangiectasia (A-T) gene have been shown to have an increased risk of breast cancer. It has been estimated that 8% to 10% of all patients with breast cancer carry an A-T mutation.1 Since patients who have homozygous or compound heterozygous A-T mutations can experience devastating necrosis of normal tissues if they receive conventional doses of radiation therapy (RT) for lymphoid tumors, patients who have single mutations would theoretically also be vulnerable to excess damage from RT. However, excessive toxicity has not been observed among such patients who were treated with RT for cancer. In fact, it is possible that because tumor cells grow more rapidly than normal cells, RT may be a particularly effective cancer treatment for patients with single A-T mutations. We examined the effects of adjuvant RT on the clinical outcomes of such patients. .... Our results suggest that, contrary to the experience with patients who are homozygous for an A-T mutation or who carry compound heterozygous mutations, adjuvant RT may be differentially beneficial to carriers of single A-T mutations with early stage breast cancer. Such benefit cannot be explained in this sample by other factors such as tumor size, nodal status, or adjuvant chemotherapy. Moreover, the substantial reduction of recurrence risks in carriers of single A-T mutations in our study was much greater than that observed in the general population, in which only a 15% to 30% improvement in disease-free survival has been found with postmastectomy RT.4 It is possible that, due to their radiosensitivity,5 tumor cells in carriers of A-T mutations are more susceptible to cell killing by ionizing radiation than are tumor cells in noncarriers. Risks of acute or long-term adverse events, if any, were apparently too small to be detected in the current sample. This could be due to the fact that, in a radiosensitive host, tumor cells growing at abnormally rapid rates demonstrate much greater sensitivity to RT than do normal cells.It is important to confirm the current finding and to obtain more precise relative risk estimates. If women with single A-T mutations were consistently found to benefit differentially from adjuvant RT, a significant number of deaths from breast cancer could be prevented or delayed. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.