Plasma ctDNA analyses have shown therapeutic benefits and can help understand tumor evolution, including mechanisms of resistance such as acquired ESR1 mutations that induce aromatase inhibitor resistance [28] in BAC and EGFR resistance to 1st and 2nd generation EGFR tyrosine kinase inhibitors in NSCLC. The gene discussed is EGFR; the disease is minimally invasive lung adenocarcinoma.