Nowadays, breast-conserving surgery is becoming more and more common, and clinical studies have shown that for early-stage breast cancer, the local recurrence rate and long-term survival rate are not statistically different when breast-conserving surgery (local excision/mastectomy ± axillary lymph node dissection/sentinel lymph node biopsy) is chosen, and breast radiation therapy is given after surgery, compared with “total mastectomy + axillary lymph node dissection”. There is no clear statistical difference in local recurrence rate and long-term survival rate. First of all, what is early stage breast cancer? The meaning of “early stage” is actually a concept used in common communication (common people’s terminology), which is rather vague and not strictly defined and standardized by an authority. TNM staging is defined in three aspects, i.e. local tumor size (T), lymph node metastasis (N) and distant organ metastasis (M). Metastasis (M). Clinicopathological staging is based on TNM staging and is divided into stages I, II, III and IV (specific criteria can be found in professional books and professional websites). From the descriptions in professional journals and the usual consensus, the so-called “early stage” refers to patients with clinical stage I. Generally, stage II refers to the middle stage, and stage II refers to the middle stage. In general, stage II refers to the middle stage, stage III refers to the middle to late stage, and stage IV is definitely advanced. What exactly is the concept of stage I breast cancer? According to the internationally recognized NCCN Guidelines (2014), there are two criteria for stage I: stage IA: tumor maximum diameter is less than 2 cm and there is no lymph node metastasis; stage IB: tumor maximum diameter is less than 2 cm and there is micro-metastasis of lymph nodes. What is meant by micrometastasis? Micro-metastasis is a tumor with metastasis in the lymph nodes that cannot be detected by examination, but can be seen under the microscope by careful pathological sectioning, and is defined by NCCN as a metastasis larger than 0.2mm or more than 200 tumor cells, but less than 2mm. Nowadays, the technical and equipment conditions of each hospital vary, and only in some large specialized centers the diagnosis rate is higher. Therefore, most patients are classified as having IA even if they have micrometastases, because they are not detected. How can we determine the presence of micrometastases without having a mastectomy or axillary lymph node dissection? The current method is the “sentinel lymph node biopsy technique”, which means that after “lymph node visualization”, a very small incision is made and the lymph node is removed for pathological section and microscopic examination (as shown in the figure below). The so-called sentinel lymph node is the first lymph node (or group of lymph nodes) that metastasizes in most breast cancers, just like the “sentinel” guarding the front line, so the image is named “sentinel lymph node”. Is stage IB with micrometastasis of lymph nodes an early stage breast cancer? There is no clear definition of early stage, and it should not be called early stage if metastasis has already appeared. However, the detection rate of micrometastases in China is still very, very low. Even in big hospitals in big cities like Beijing and Shanghai, the actual detection of micrometastases is not high (the specific values can be found in related articles), let alone in other places. That’s why people still call stage I early, so it includes stage IB. What is the accepted standard of care for early stage breast cancer? Since the 1990s, the accepted treatment is “breast-conserving mastectomy + whole-breast radiotherapy”, and after observing and studying a large number of patients, the local recurrence rate and long-term survival rate are basically the same as the traditional excision of the whole breast and axillary lymph. If you are not sure about the margin of excision, you can expand it appropriately and do a mastectomy. What if the lymph nodes are diagnosed to have micrometastases through the anterior lymph node examination? In this case, if micrometastases are found, the guidelines recommend that the lymph nodes around this group of lymph nodes can be slightly enlarged and the whole axillary lymph nodes can be removed, and postoperative adjuvant radiotherapy can be given. In my personal opinion, the former can be chosen for those who have the conditions, higher level of knowledge and culture, and better economic conditions, but it is better to have the whole axillary lymph nodes cleared for those who have less conditions or patients. Is it necessary to do radiotherapy after breast-conserving surgery? According to research data and accepted opinion, most do. Radiotherapy is an important part of breast-conserving surgery protocol. Early stage breast cancer, especially to detect micro-metastases in lymph nodes is not that easy, and radiotherapy can make up for the lack of surgical resection. When can breast-conserving surgery be done without radiotherapy? The clinical trial number CALGB-9343 reported the results of the study in 2013 and concluded that patients older than 70 years with clean resection and positive ER receptors (patients who are positive on estrogen receptor staining) can be treated without radiotherapy, and oral anti-estrogen drugs (triamcinolone acetonide) alone are sufficient, and oral triamcinolone acetonide is recommended for about 5 years.