Rationale: Patients with, or who develop, metastatic breast cancer have a 5-year relative survival of about 25%. Endocrine therapy clearly improves outcomes in patients with estrogen receptor-positive breast cancer. In the metastatic setting, the primary goal of treatment is to maintain long-term disease control with good quality of life. Rarely, exceptional responders achieve durable disease control, and potential cures cannot be ruled out.Patient Concerns: We report the case of a 39-year-old woman with primary breast cancer and associated synchronous bone metastases, who experienced a disease response of 12 years with hormonal therapy as maintenance after first line chemotherapy, with a good toxicity profile.Diagnosis: The patient was diagnosed with estrogen receptor + human epidermal growth factor receptor 2 (HER2)- metastatic breast cancer with synchronous bone metastases.Interventions: This patient was treated with chemotherapy for 6 cycles as a first-line therapy following by endocrine treatment given as a maintenance therapy.Outcomes: Our patient experienced a progression-free survival >12 years with an exceptionally good quality of life.Lessons: Our anecdotal experience highlights the existence of exceptional responders among patients with hormone receptor-positive metastatic breast cancer, who achieve clinical remission and durable disease control with endocrine therapy. Being able to identify these patients could help in the selection of the best treatment option among the many available.
