Univariate Cox proportional hazard regression with the Wald X2 test identified 30 DNA repair genes (XRCC3, DNPH1, RNF4,XRCC4, ERCC1, RAD23B, ALKBH2, HLTF, UBE2A, MUS81,XRCC1, RBBP8, RAD1, NUDT18,RAD50, PNKP, FAAP20, RPA3, ENDOV, DDB2, POLL, RAD54B, ERCC5, UBE2V2,MRE11, MPG, RRM2B, PARG,PARP3, andBRCA1) as prognosis indicators for breast cancer (Figure 2A). This evidence concerns the gene XRCC4 and breast cancer.