Subsequent studies found CDKN2A methylation in the plasma of 7/74 (9%), 3/33 (9%), and 4/50 (8%) of cancer-free controls (Belinsky et al., 2005; Hsu et al., 2007; Zhang et al., 2011), while methylation among patients with cancer included values of 25/110 (22%), 21/55 (38%), and 61% sensitivity (Wang et al., 2006; Hsu et al., 2007; Zhang et al., 2011). Here, CDKN2A is linked to cancer.