How would you approach a young patient with ER+/Her2- bilateral breast cancer with a solitary bone metastasis?

I'm assuming from the question that this is a de novo Stage IV. Assuming a biopsy confirms metastatic breast cancer, I'd start such a patient on the appropriate endocrine therapy. I'd wait on considering loco-regional therapy until there has been a response. This reduces the risk of pursuing loco-regional therapy in a patient who has relatively refractory disease, and because there is some data that the risk of death is reduced among such patients if they undergo surgery after systemic therapy (Lane et al, Ann Surg 2019). Waiting also provides more time to spend counseling the patient about the intent, risks and benefits of loco-regional therapy in de novo Stage IV.

Assuming benefit from first-line therapy, I would try to add definitive loca...