We report a case of advanced left breast cancer with continuous bleeding from the primary tumor surface in an 81-year-old woman. Pathological findings showed invasive carcinoma with positive expression of hormone receptors. CT and bone scintigraphy showed primary tumor invasion of the greater pectoral muscle and multiple bone metastases. She received Mohs' chemosurgery, endocrine therapy, and denosumab. The bleeding was maintained by weekly treatment. Most of the bulging surface of the tumor decreased and dried up 2 months later. The tumor disappeared almost completely, and the bone metastases achieved stable status 3 months later. Until currently, the primary tumor and metastasis have been controlled for 1.5 years. Mohs' paste was effective for controlling bleeding and exudates of unresectable cancer bulging from the skin surface and played an important role in cancer treatment with systemic therapy.