Chemotherapy is a commonly used treatment for breast cancer that can effectively kill cancer cells. However, tumor recurrence may occur after chemotherapy for breast cancer. This may be because breast cancer cells cannot be completely killed during chemotherapy, or some cancer cells have developed resistance to chemotherapy drugs. In addition, the effects of chemotherapy on the body may also cause new cancers to occur. Therefore, regular checkups should be conducted after chemotherapy for breast cancer, and attention should be paid to maintaining a healthy lifestyle to reduce the risk of cancer recurrence.