PARP1 and breast cancer: According to our results, there was significant statistical heterogeneity in the PFS of the ovarian cancer subgroup (HR, 0.50; 95%CI, 0.32–0.80), while in the lung (HR, 0.98; 95%CI, 0.83–1.15) and breast cancer groups (HR, 0.72; 95%CI, 0.56–0.94), there seemed to be no odds difference between the PARP inhibitor and control arms.