Similarly, numerous studies all around the world could not confirm a significant association between PD-1 rs2227981 and susceptibility or protection to BC (Haghshenas et al., 2011), colorectal cancer (Savabkar et al., 2013), NSCLC (Ma et al., 2015) and epithelial ovarian cancer (Li et al., 2016). This evidence concerns the gene PDCD1 and breast cancer.