IntroductionChemotherapy and other systemic therapies are the primary treatments for patients with unresectable, locally advanced breast cancer. The clinical application of supportive care using Mohs paste has become widespread for the purpose of improving patients’ quality of life. Here, we report two cases of locally advanced breast cancer, for which the patients underwent radical surgery after a combination of systemic therapy and Mohs chemosurgery.Case presentationsPatient 1 was a 90-year-old Japanese woman with right breast cancer diagnosed as stage IIIB (T4bN1M0). The treatment included Mohs paste application and hormonal therapies. Patient 2 was a 60-year-old Japanese woman with right breast cancer diagnosed as stage IIIB (T4cN2aM0). Her treatment included Mohs paste application, together with chemotherapy (four cycles of 5-fluorouracil, epirubicin, and cyclophosphamide, and four cycles of docetaxel). In both cases, a reduction in the primary tumor volume was observed, and radical mastectomy and axillary lymph node dissection were possible without relaxation incision or skin flap.ConclusionWe report patients with no distant metastases who were able to undergo radical resection after a combination of systemic therapy and Mohs chemosurgery. For locally advanced breast cancer, Mohs chemosurgery, in addition to multidisciplinary treatment, is useful.