The FDA approval of camizestrant (Etcamah) provides a new option for patients with ESR1-mutated HR+/HER2– advanced breast cancer and strengthens the case for ctDNA-guided switching. In an interview-led piece, Dana-Farber’s Erica L. Mayer discussed the SERENA-6 data supporting an early switch strategy once ESR1 mutations emerge in circulating tumor DNA. According to Mayer, initiating camizestrant with a CDK4/6 inhibitor at molecular progression—before clinical deterioration—improved progression-free survival and delayed quality-of-life worsening compared with continuing aromatase inhibitor therapy. The discussion also emphasized camizestrant’s role as part of a growing set of oral endocrine agents. Clinically, the approval shifts practice toward monitoring resistance mutations and intervening earlier, with ongoing questions centered on how to operationalize ctDNA screening in routine care.