1. A method for using DNA repair capacity (DRC) as a blood biomarker to calculate the risk of a female subject developing breast cancer, comprising: a) obtaining lymphocytes isolated from the subject wherein the lymphocytes comprise non-replicated expression plasmids comprising a luciferase reporter gene that has been exposed to ultraviolet radiation C (UVC); b) calculating a percent DRC for the subject as the percentage of residual luciferase gene expression after repair of damaged plasmid DNA as compared to luciferase gene in cells comprising non-replicating expression plasmids comprising a luciferase reporter gene that has not been exposed to UVC; and c) classifying a subject with a percent DRC below 3.1% as being at risk for breast cancer and classifying a subject with a percent DRC above 3.1% as being at low risk for breast cancer.