Of the 318 genes significant (FDR < 10%) for the progressive/recurrent tumor group, 222 were not significant for either the initial tumor group or the entire tumor set (Fig. 6b, c), these genes including CCND2 (cyclin D2) and NTRK1. In addition to issues involving sample power and sensitivity, the differences in the associations made between tumor subsets could involve SSV events being randomly distributed among initial tumor and primary/recurrent groups. This evidence concerns the gene CCND2 and neoplasm.