For a patient with breast cancer s/p lumpectomy found to have a heterozygous RAD50 mutation, is adjuvant radiation appropriate therapy or would you recommend completion mastectomy?  

Rad50 is part of the homologous recombination repair pathway. If cancer cells have homozygous loss of Rad50, they will be exquisitely sensitive to radiation therapy, which causes lethal DNA double-strand breaks via oxygen free radicals. Theoretically, adjuvant radiation is an excellent treatment bas...