Diagnosis and Prognostication of Ductal Adenocarcinomas of the Pancreas Based on Genome-Wide DNA Methylation Profiling by Bacterial Artificial Chromosome Array-Based Methylated CpG Island Amplification
Figure 2
Establishment of criteria for diagnosis of ductal adenocarcinomas of the pancreas. (a) Scattergrams of the signal ratios in samples of normal pancreatic tissue obtained from patients without ductal adenocarcinomas (C), noncancerous pancreatic tissue obtained from patients with ductal adenocarcinomas (N) and cancerous tissue (T) on representative BAC clones, RP11-88P10 and RP11-424K7. Using the cutoff values indicated by the dotted lines, T-samples were discriminated from both C- and N-samples in the learning cohort with 100% specificity. (b) Histogram showing the number of BAC clones satisfying the criteria listed in Table 2 in the learning cohort (). C-, N- and T-samples are indicated by empty, shaded, and filled columns, respectively. Based on this histogram, we established the following criteria: when the tissue samples satisfied the criteria listed in Table 2 for 1 or more BAC clones (dotted line), they were judged to be cancerous tissue, and when tissue samples did not satisfy the criteria for any BAC clone, they were judged not to be cancerous tissue. Based on these criteria, both the sensitivity and specificity for diagnosis of T-samples in the learning cohort as being cancerous were 100%. (c) Validation of the above criteria using 68 additional tissue samples in the validation cohort. All 45 validation samples satisfying the criteria in Table 2 for 1 or more BAC clones (dotted line) were T-samples (filled columns), and all 23 validation samples not satisfying the criteria in Table 2 for any BAC clone were C- (empty column) or N- (shaded column) samples. Both the sensitivity and specificity for diagnosis of T-samples in the validation cohort as being cancerous were again 100%.
