Metastatic male breast cancer: complete metabolic response after restarting anastrozole, leuprolide, abemaciclib, zoledronic acid, and radiation

What happened, in summary

This 60-year-old man had COPD, tobacco use disorder, and a diagnosis of Stage IV metastatic breast cancer made 3 years before this admission. He came to the emergency department with sudden severe pain in his lower back and left leg. Examination showed an indurated, erythematous area near the left nipple and tenderness in the upper left lower extremity. CT of the thoracic and lumbar spine showed diffuse sclerotic and lytic replacement of vertebral bodies T2-T6, destructive lesions extending through the pedicles, especially at T5, and additional lytic and sclerotic lesions at L1 and L5. Biopsy of a bone lesion confirmed metastatic breast cancer. His original breast workup had shown a 33 mm subareolar mass and a smaller axillary-tail mass in the left breast, with left axillary adenopathy, a left paratracheal soft-tissue mass, and bone lesions. Core biopsy confirmed grade 1 invasive ductal carcinoma that was strongly hormone receptor-positive, with ER greater than 95%, PR greater than 95%, HER2/neu-negative status, and Ki-67 of 30%. Tumor sequencing showed a pathogenic PIK3CA exon 21 variant, while BRCA1 and BRCA2 were not mutated. He had been started on anastrozole plus Lupron/leuprolide, followed by abemaciclib, zoledronic acid, and palliative radiation, but treatment was interrupted because of resource, insurance, follow-up, and stigma-related barriers. During admission, he received multimodal pain treatment and dexamethasone. Neurosurgery did not recommend acute intervention. Abemaciclib and anastrozole were restarted, and outpatient therapy continued with leuprolide, anastrozole, and abemaciclib. Radiation improved his back pain. As of May 2025, his last 2 PET scans showed complete metabolic response without disease progression, and brain MRI showed no metastasis.