Breast Cancer Discovered After Widespread Bone Metastases

What happened, in summary

A 44-year-old woman was being evaluated for flank pain and a kidney infection when CT imaging unexpectedly showed widespread abnormal changes in her bones. MRI found diffuse abnormalities throughout the cervical, thoracic, and lumbar spine as well as the sacrum and pelvis, raising concern for metastatic cancer or a plasma cell disorder. A screening mammogram one month earlier had been read as negative. Bone marrow biopsy then revealed metastatic invasive ductal carcinoma consistent with a breast primary. The cancer was strongly estrogen- and progesterone-receptor positive, HER2-negative, and had a low Ki-67 of 5%. Targeted breast imaging later found a small 5 × 3 mm mass in the left breast and a markedly enlarged left axillary lymph node. Biopsy of the axillary node also confirmed metastatic invasive ductal carcinoma of breast origin. Her disease was classified as Stage IV because of the extensive bone and bone marrow involvement. Germline testing was negative for BRCA1 and BRCA2 mutations. Because she was premenopausal, she underwent bilateral oophorectomy for ovarian suppression. She then began letrozole together with the CDK4/6 inhibitor ribociclib. At the time of the report, she was continuing this systemic treatment for hormone receptor-positive, HER2-negative metastatic breast cancer.