Surgical removal of a breast cancer tumor is not a “once and for all” solution. The possibility of recurrence still exists, but not all breast cancer patients will experience recurrence. This requires an explanation of the concept of “micrometastasis” in breast cancer. Micrometastases are breast cancer metastases that cannot be detected by conventional clinical and imaging methods. About 50% of breast cancer patients with no distant metastases detected in preoperative examinations have micro-metastases in their bodies, which are the source of future distant metastases. The current level of technological development cannot accurately assess the occurrence of micrometastases, and we can only speculate the probability of micrometastases based on clinicopathological indicators such as regional lymph node metastasis and immunohistochemistry. After regular treatment, there may be latent micrometastases, so we should review regularly after regular treatment in order to detect distant metastases early, treat them earlier and prolong life. There are already some clinical indicators and laboratory tests that can be used to evaluate the risk of recurrence. Generally speaking, the risk of breast cancer recurrence is highest within 5 years after the initial diagnosis, and the possibility of recurrence exists after 5 years, but the probability decreases.