Notably, the purity estimates produced by ABSOLUTE appeared to be more accurate for the bulk tumor than those derived from histological examination of frozen tumor sections (Online Methods, Fig. 2e). Estimates of the proportion of contaminating normal cells for 458 ovarian carcinoma samples33 produced by ABSOLUTE were strongly correlated with a molecular signature of genomic methylation (Online Methods) seen in leukocytes (r2 = 0.59, P < 2.2×10-16, Fig. 2e), but only weakly correlated with estimates of contamination from histological examination (r2 =0.1, P = 2.4×10-12; Online Methods; Fig. 2e x-axis scale, Supplementary Fig. 4).
