1. How should early, middle and late stages of breast cancer be defined? People generally like to classify cancer into early, middle and late stages, which literally means that the closer to the late stage, the more serious the disease is. In reality, most cancers have early, middle and late stages, and the survival time is closely related to the stage. Although the staging of breast cancer is not called early, intermediate or late, its meaning is similar. Professionally, according to the early or late detection of breast cancer, it can be divided into early, locally advanced and late stages. The so-called advanced stage refers to breast cancer with metastasis from liver, lung, bone, brain and other organs, which is the same as what the people call late stage cancer. The more special kind of breast cancer is locally advanced, which refers to breast with large lumps or many lymph nodes metastasis, and some breast with red and swollen skin but no distant organ metastasis, this kind of cancer still has a chance of cure, but the prognosis is worse than early stage. Early stage breast cancer is the mainstream at present, which refers to those breast cancers with lumps that are not too big and no lymph nodes metastasis or not many metastasis. 2.What are the symptoms of early stage breast cancer? Patients often come with doubts and ask, “I don’t feel anything at all, how can I have breast cancer? In general, people usually understand the feeling as pain, once they have pain, they will feel themselves “sick”. But unfortunately, most of the breast cancers are painless, especially the early stage breast cancers. The most common symptom of breast cancer is a hard lump in the breast, which is not painful, not itchy, and basically not uncomfortable. The second common symptom is nipple discharge. It is important to note that many early stage breast cancers do not have symptoms, neither conscious discomfort nor lumps and overflow. This type of breast cancer can only be detected through health checkups, through imaging tests such as ultrasound and mammogram. This type of breast cancer may account for more than half of the cases in Europe and the United States because most western countries have national screening services, while screening in China is not well done and most rely on patient-initiated examinations. 3.What is the significance of early detection of breast cancer for the treatment of breast cancer? We emphasize early detection of breast cancer because the earlier it is detected, the higher the hope of cure. The development process of breast cancer follows from mutation in genes → abnormal proliferation of breast duct epithelium → the earliest carcinoma in situ (confined to the localized breast and will not metastasize) → cancer cells enter the blood vessels and lymphatic vessels → metastasis occurs in other organs and forms metastatic cancer. Therefore, in order to cure breast cancer, it is necessary to grab the breast cancer before it enters the circulatory system and appears to spread. The earliest stage of carcinoma in situ is clinically curable and most patients do not die from breast cancer. The percentage of in situ cancer in western countries is very high, while the average percentage in China is about 6%, and the percentage in Peking University People’s Hospital is about 20%, which is related to the fact that our imaging examination is done more meticulously and accurately. Early stage tumors are relatively simple to treat, and most of them can be cured by surgery. As the tumor progresses, treatments with greater side effects such as chemotherapy and radiotherapy may be needed, which is why we emphasize early detection of tumors. There is no specific drug for breast cancer, and the efficacy is closely related to the stage, so early detection and standardized treatment is the key to improve the treatment effect of breast cancer.