Do you recommend using a ctDNA assay for a patient with HER2+ metastatic breast cancer in a continued CR to guide decision about whether to stop anti therapy?

This is a good question and is not a rare situation in the management of HER2+ metastatic breast cancer. Radiographic complete response occurs with first-line treatment in 6-15% (CLEOPATRA, GIM-14, and other trials). Currently, the standard of care is to continue anti-Her2 therapy indefinitely. Howe...