Studies conducted on different types of cancer show several contradictory results, where some studies have shown an association between some SNPs in XRCC3 and a risk of colorectal cancer, gastric cancer, breast cancer, colorectal cancer, lung cancer, glioma and meningioma, liver cancer, or head and neck cancer [3, 22–29], while other studies have failed to show any association [30, 31]. The gene discussed is XRCC3; the disease is gastric cancer.