Almost all guidelines for bladder (n=9, 90.0%), colorectal (n=15, 83.3%), kidney (n=7, 100%), liver (n=4, 80.0%) and lung (n=5, 83.3%) recommend using CT scans in surveillance for at least some patients; whereas, for prostate, breast and brain cancers, no guidelines recommend the use of CT scans (instead PSA testing, mammograms and MRI are recommended respectively). The gene discussed is KLK3; the disease is brain cancer.