Euclidean distance and heatmaps of the in situ and invasive samples using the classifiers obtained after cross-validation. (a) All ductal carcinoma in situ (DCIS) (n = 40) and all invasive (n = 40) samples. The classifiers consist of 80 genes. (b) Poorly differentiated DCIS (n = 14) versus invasive grade 3 samples (n = 24) using a classifier of 35 genes. p, poorly differentiated.