As another example, ctDNA analysis in BR28 showed that EGFR p.R521K and PTCH1 p.T1195S variants were more frequent than ATM pH1380Y, BRCA2 p.N289H, and BRCA2 p.N991D, whereas all these variants were present at a similar frequency in tumor tissue samples at diagnosis and after the 1st NAC cycle. The gene discussed is PTCH1; the disease is neoplasm.