BRCA1 and breast cancer: Current guidelines indicate that patients with BRCA1/2m-related BC are not eligible for accelerated partial breast irradiation,19 but that is based on lack of data rather than evidence for increased toxicity or decreased efficacy with accelerated partial breast irradiation; patients with BRCA1/2m-related BC were excluded from accelerated partial breast irradiation studies because they carry a high risk for second primary BC.