IDH2 and neoplasm: A recent work produced by Csoma et al. [31] found a positive correlation between cfDNA yield and the estimated tumor volume; when comparing liquid biopsy results to those from tissue analysis, a similar tumor variant burden (TVB) was reported and some of the most relevant aberrations in BTC—such as those involving FGFR2, IDH1, IDH2, KRAS, and TP53—could be detected in both samples; interestingly, in 2 cases, only the serum sample had been informative for molecular assessment.