Frequency of prognostic factors and survival probability in PCA clusters. A. The frequency of prognostic factors in the four PCA clusters p1-p4 for the De Preter data set (n = 17) and McArdle/Wilzén (n = 30). High stage (3-4) = INSS stage 3 and 4; DOD = Dead of disease; MNA = MYCN amplification; Del = deletion. Significant occurrence of prognostic factors in one PCA cluster compared to the others is marked with stars (Fisher's exact test). n = the number of samples in each subgroup. B. Kaplan Meier survival curves of PCA clusters (p1-p4) from three data sets (De Preter, McArdle, and Wilzén). OS = Overall survival (n = 43). EFS = Event-free survival (n = 35). Chi-square significance by Log-rank (Mantel-Cox).