The numbness of feet of breast cancer patients after chemotherapy may be caused by peripheral nerve damage due to chemotherapy, or due to poor blood circulation or herniated lumbar disc. 1. Peripheral nerve damage: When patients undergo chemotherapy, it may cause damage to the body and cause adverse reactions, such as headache, dizziness, nausea, diarrhea and so on. It may also cause some damage to the patient’s nerve endings tissue, thus causing numbness of the feet. 2. Poor blood circulation: patients may have a loss of appetite during chemotherapy, resulting in malnutrition, making the body’s blood circulation worse, resulting in ischemic numbness at the end of the body. 3. Herniated lumbar disc: Herniated lumbar disc will lead to compression of sciatic nerve, and at the initial stage, patients may have pain in legs and feet, and with the development of the disease, the pain will gradually develop into numbness. Breast cancer patients should seek medical examination and treatment in time if they feel unwell after chemotherapy.