I have a 43 year old premenopausal woman with de novo Stage 4 Triple Positive Breast Cancer (ER/PR 70%, HER 2 3+) with brain and lung mets. Got SBRT to brain for lesions. Now starting docetaxel plus dual her2. My question is what is your approach to endocrine therapy and ovarian suppression in this setting. When do you start or is it even needed and if so, is it ok to combine with chemo/HER2 treatment?
For triple-positive disease, I usually try to administer at least 6 cycles of THP, then if good disease response, stop the docetaxel and start endocrine therapy. In CLEOPATRA, concurrent chemo and endocrine therapy was not allowed- probably based on some older studies that showed that concurrent administration was detrimental. I usually don't ever administer cytotoxic chemo with endocrine therapy, as the endocrine agent causes cellular senescence, and chemo works better on rapidly-dividing cells. Removal of the chemo agent and adding an endocrine therapy agent after 6 cycles of THP allows for a good maintenance strategy and minimizes chemo-induced toxicities.
