The high incidence of breast cancer is the trend today, and the key to good or bad outcome is the stage where the lesion is confined and the immune system is intact. When patients present with a lump and are diagnosed with breast cancer, most of them have bloodstream metastases and are no longer at an early stage. Therefore, when prevention from the etiology is not yet possible, strengthening the awareness of early diagnosis, fully considering the susceptibility factors and paying attention to the early diagnosis strategy of breast cancer will be the development direction to improve the survival rate of breast cancer. The key to the efficacy of breast cancer, like other cancers, lies in the stage when the lesion is confined and the immune system is intact. However, the early stage of breast cancer often has no conscious symptoms and is not easily detected clinically when it has not yet formed a mass or is extremely small, and by the time a patient finds a lump and goes to the hospital, it may have already metastasized distantly or is latent in the body in the form of micrometastases, leading to the ultimate failure of treatment. Therefore, in the current situation that breast cancer cannot be prevented from its etiology, strengthening the awareness of early diagnosis, attaching importance to the early diagnosis of breast cancer in situ and metastasis, and implementing standardized and comprehensive treatment measures are the best ways to reduce disabling factors, increase the cure rate, reduce mortality and improve the quality of life. 1.Early diagnosis of primary breast cancer The survival rate of breast cancer patients is related to the stage of cancer. The data show that the 5-year and 10-year survival rates of stage I patients are 90.9% and 83.7% respectively; stage II patients are 78.0% and 65.8% respectively; stage III patients are 53.5% and 43.0% respectively, while the 5-year survival rate of metastatic breast cancer patients (stage IV) (23%) is lower than that of stage III breast cancer patients (79%) and I-II breast cancer patients (97%). The key to improving breast cancer survival and reducing mortality is early detection. The modern concept of earlybreast cancer (EBC) is that the lesion is at an early histological or clinical stage. The cancer is confined to the breast, without distant or regional lymph node metastasis; and more than 90% of the patients can achieve long-term survival after local treatment. Histologically, it can include lobular carcinoma in situ, non-invasive intraductal carcinoma, papillary Paget’s disease (invasive carcinoma without lump), and early invasive carcinoma; clinically, it can include carcinoma in situ, T0 carcinoma (clinically non-palpable lump), and microscopic carcinoma (carcinoma of 5 cm diameter). For example, in the United States, although the newly increased incidence rate is as high as 1/7, the mortality rate continues to decrease at a rate of 2.2% per year, and the survival rate is on the rise, which is related to the propaganda of self-examination of breast and regular medical check-ups and censuses, so that the proportion of some asymptomatic early cancers has increased significantly. The incidence rate in China has also increased significantly in the past 20 years, with a younger trend (10 years earlier than the West, the proportion of 30-39 years old age group is more than 20%, especially in Shanghai, Beijing, Tianjin and coastal cities, and has jumped to the first and second place of female malignant tumors, but the current diagnosis rate of early breast cancer is still low compared with foreign countries. Early diagnosis is a multidisciplinary diagnosis including clinical examination, self-examination, imaging and molecular biology, etc. WHO has ranked breast cancer as one of the most effective tumors after cervical cancer in cancer prevention screening. It is expected that in the new century, the prevention and treatment strategy will evolve from “find and destroy” to “target and control”. 1.1 Clinical examination and self-examination is the first step in early detection of breast cancer. We should abandon the traditional concept that “non-breast lumps are not cancer”, pay attention to valuable “traces”, and establish a new concept of “prevention and treatment”. The new concept of “prevention by treatment” should be established. In the diagnosis, we should attach great importance to the medical history and perform risk assessment through a comprehensive analysis of epidemiology, breast pathology and relevant biomarker tests. Early menarche, late menopause, older unmarried, older infertile, not breastfeeding after delivery, more frequent abortions, high fat diet, overweight, more exposure to radiation, maternal history of breast cancer, long-term smoking and alcohol abuse, estrogen use, wearing inappropriate bras and genetic mutations are undoubtedly the key targets. One should also be familiar with various subtle signs and symptoms of early breast cancer: such as nipple overflow or blood spill, nipple skin desquamation or erosion, mild small depressions of breast skin, limited glandular thickening that does not change with the menstrual cycle, cystic hyperplasia that does not improve with medication, and postmenopausal breast pain. It has been reported that the proportion of non-invasive cancer found in western countries is 20%, and the cases of early stage cancer are as high as 40%. In China, women have less fat and more glands, and the age of onset is early, so the conditions are not yet available for extensive X-ray screening, so the early diagnosis rate is low. However, T0 cancer or subclinical cancer has been reported in the last century, mainly because of the importance of the manifestations such as limited glandular thickening, nipple overflow, nipple erosion, mild nipple retraction, and mild edema of the areola, which can be avoided or reduced by combining with X-ray radiography, and is beneficial to the early diagnosis of breast cancer. Regarding self-examination of breast, although some prospective studies have not found any association with improved survival rate, it is still worth advocating in China. The combination of self-examination and medical examination by professional physicians is a desirable method for early diagnosis.