PARP1 and breast cancer: Cox regression analysis showed that high expression levels of PARP1 and TNF-α were a risk factor for distant metastasis after breast cancer surgery (RRPARP1 = 4.092, 95% CI 2.475–6.766, P < 0.001; RRTNF-α = 1.825, 95% CI 1.189–2.799, P = 0.006).