Do you ever change treatment for metastatic breast cancer with rising tumor markers, but no evidence of progression on imaging?

I do not change treatment based on just tumor markers in advanced breast cancer. When there is significant rise in the level of tumor markers, one should be following the patient closely since this could be an indication of disease progression about to declare itself. There are no well conducted large studies where treatment changes were made solely based on tumor markers, hence using them as a stand alone measure to decide treatment is not backed by evidence. Although several studies have shown...