Fig. 2
From: Brush swab as a noninvasive surrogate for tissue biopsies in epigenomic profiling of oral cancer
The scatterplots demonstrate the correlation between tissue and brush swab biopsies for (A) cancer and (B) normal sites of the 3 patients. The correlation values are noted. (C) By focusing on the top 1000 most variable methylation features between cancer and normal samples quantified with MC-Seq, we determined the methylation difference between different sample types, visualized using box plots (median, quartiles, maximum and minimum whiskers). The p-values for each test of difference in CpG methylation by t-test were expressed as -log10(p-value), which had a median of 3.67 (i.e., p = 0.00021) between cancer vs. normal. The same CpG sites were not differentially methylated [average -log10(p-value) = 0.96 (i.e., p = 0.11)] between tissue vs. brush swabs, suggesting that brush swabs are a viable surrogate of tissue biopsy