The female breast is composed of skin, fibrous tissue, mammary glands and fat. Breast cancer is a malignant tumor that occurs in the glandular epithelial tissue of the breast. Breast cancer occurs in 99% of women and only 1% of men. Breast cancer in situ is not fatal because it is not a vital organ that sustains the body’s life activities; however, because breast cancer cells lose the characteristics of normal cells, they are loosely connected to each other and can be easily shed. Once the cancer cells are shed, the free cancer cells can spread throughout the body with blood or lymphatic fluid, forming metastasis and endangering life. Currently, breast cancer has become a common tumor threatening women’s physical and mental health. The global incidence of breast cancer has been on the rise since the late 1970s. One out of eight women in the United States will develop breast cancer in their lifetime. China is not a country with high incidence of breast cancer, but it should not be optimistic. In recent years, the incidence rate of breast cancer in China has been increasing at a rate 1 to 2 percentage points higher than that of countries with high incidence. According to the 2009 breast cancer incidence data released by the National Cancer Center and the Bureau of Disease Prevention and Control of the Ministry of Health in 2012, the incidence of breast cancer in the national tumor registration area ranked 1st among female malignant tumors, and the incidence rate (crude rate) of female breast cancer was 42.55/100,000 nationwide combined, 51.91/100,000 in urban areas and 23.12/100,000 in rural areas. Breast cancer has become a major public health problem in the current society. The global breast cancer mortality rate has shown a decreasing trend since the 1990s; the reasons for this are, firstly, the screening of breast cancer, which has increased the proportion of early cases; and secondly, the development of comprehensive breast cancer treatment, which has improved the efficacy. Breast cancer has become one of the solid tumors with the best curative effect. Clinical manifestations Early stage breast cancer often does not have typical symptoms and signs and is not easy to attract attention, but is often detected through physical examination or breast cancer screening. The following are the typical signs and symptoms of breast cancer. Breast lumps 80% of breast cancer patients are first diagnosed with breast lumps. Breast lumps are often found unintentionally, most of them are single, hard, with irregular edges and less smooth surface. Most breast cancers are painless lumps, only a few are accompanied by varying degrees of vague pain or stabbing pain. Nipple overflow is called nipple overflow when there is blood, plasma, milk or pus flowing from the nipple during non-pregnancy period, or when there is still milk flowing after stopping breastfeeding for more than half a year. There are many causes of nipple overflow, and common diseases include intraductal papilloma, mastopexy, ductal dilatation and breast cancer. Unilateral hemorrhagic overflow from a single hole should be further examined, and more attention should be paid if it is accompanied by breast lumps. The most common one is that the tumor invades Cooper’s ligament which connects the breast skin and deep pectoral muscle fascia, causing it to shorten and lose its elasticity, pulling the skin of the corresponding area, resulting in “dimple sign”, i.e. a small dimple in the breast skin, like a small dimple. If the cancer cells block the lymphatic ducts, “orange peel-like changes” will appear, i.e. the skin of the breast will have many small dots and depressions, just like an orange peel. In advanced stage of breast cancer, the cancer cells infiltrate into the skin along the lymphatic ducts, glandular ducts or fibrous tissues and grow into the skin, forming scattered hard nodules around the main cancer site, which is called “skin satellite nodules”. 4.Abnormality of nipple and areola Tumor located in or close to the deep part of nipple may cause nipple retraction. If the tumor is far away from the nipple, it may also cause nipple retraction or elevation when the large duct in the breast is invaded and shortened. Eczema-like carcinoma of the nipple, i.e. Paget’s disease of the breast, manifests as itching, erosion, rupture, crusting, flaking and burning pain of the nipple skin, resulting in nipple retraction. 5. Axillary lymph node swelling More than 1/3 of breast cancer patients admitted to large hospitals have axillary lymph node metastasis. Initially, the lymph nodes in the axilla on the same side may be enlarged, and the enlarged lymph nodes are hard, scattered and pushable. As the disease progresses, the lymph nodes will gradually fuse and adhere to the skin and surrounding tissues. In the advanced stage, metastatic lymph nodes can be felt in the supraclavicular and contralateral axillae.