After 31 months of follow-up with no visible tumor lesions by MRI, cfDNA levels increased to 1.99 ng/μL, and a total of 37 mutations were detected in the cfDNA distributed along the five genes tested: TERT (16), TP53 (9), AXIN1 (6), ARID1A (4) and CTNNB1 (2) (Figure 5B). The gene discussed is ARID1A; the disease is neoplasm.