XRCC6 and cancer: Moreover, we find that there are 12 methylation regions (i.e., located within ACAA2, NUSAP1, OGFOD1, PSMD5, SNRNP40, USP37, XRCC6, CCL18, DPP6, GRIK3, LZTFL1, and LACTB) that not only have non-zero total effect on the survival risk, but also have substantial direct influence on the survival risk of cancers.