To accent the increased sensitivity of detection, the results of 1 patient with advanced PCa (9 months follow-up; 7 blood sample collections) are also shown in Figure 4A. Although the unmethylated G-116bp background signal was relatively constant during the whole measurement period, highly variable levels of methylated GSTP1 DNA fragments were detected in 5 out of 7 samples collected at the different time points during anti-cancer therapy. This evidence concerns the gene GSTP1 and posterior cortical atrophy.