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 that threatens women’s physical and mental health. Early symptoms of breast cancer 1. Lumps: The outer upper quadrant of the breast is the preferred site of breast cancer. Lumps are often painless, single, irregular, mostly solid, hard and less mobile. Local skin changes: The “dimple sign” of breast skin is an important sign, which is caused by the pulling of Cooper’s ligament or the adhesion between the tumor and the skin. When cancer cells block the subcutaneous lymphatic vessels, orange peel edema may appear, and some of them may have varicose veins and satellite nodules. 3. Nipple changes: When the lesion invades the nipple or subareolar area, the fibrous tissue and duct system of the breast can be shortened by tumor invasion. Further development of the lesion may cause the nipple to flatten, retract and sink until it is completely shrunken under the areola and the nipple cannot be seen. Nipple erosion is also an important sign of breast cancer. 4. Nipple overflow: Nipple overflow can occur from epithelial hyperplasia, inflammation, bleeding, necrosis and tumor of breast ducts, especially large ducts. The overflow can be five-colored, milky white, yellowish, brown, bloody, etc. It can be watery, bloody, plasma or purulent. Blood is more common in breast cancer and is often found by patients due to contamination of painful underwear. 5. Pain: A few patients have vague pain or stabbing pain. Middle and late stage symptoms of breast cancer Breast lump is the most common symptom of breast cancer, and about 90% of patients come to the clinic with this symptom. With the popularization of tumor knowledge and cancer screening, this percentage may increase. If a lump appears in the breast, the following aspects should be understood. 1. Location: With the nipple as the center and a cross, the breast can be divided into 5 zones: upper inner, upper outer, lower inner, lower outer and central (areola). Breast cancer is more common in the upper part of the breast, followed by the upper part of the breast. Lower internal and lower external areas are less common. 2.Number: Breast cancer is most common in unilateral breast with a single lump, unilateral multiple lumps and primary bilateral breast cancer are not common in clinical practice. However, with the improvement of tumor prevention and treatment, patients’ survival period will be prolonged, and the chance of second primary cancer in the opposite breast will increase after surgery of one side of breast cancer. 3.Size: The lump of early breast cancer is usually small and sometimes it is not easy to distinguish from lobular hyperplasia or some benign lesions. However, even a small lump can sometimes involve the suspensory ligament of the breast and cause symptoms such as local skin indentation or nipple retraction, which are easier to detect at an early stage. In the past, due to poor health care, lumps were often larger when they came to the clinic. Nowadays, with the popularization of breast self-examination and screening, there is an increase of early breast cancer in clinical practice. 4.Morphology and boundary: Most of the breast cancers are infiltrative in growth and the boundary is not clear. Some of them may be flattened, with an unsmooth surface and nodular feeling. However, it should be noted that the smaller the lump is, the less obvious the above mentioned symptoms are. Moreover, a few special types of breast cancer can be less infiltrated and have a swollen growth, showing smooth, active and clear borders, which are not easily distinguished from benign tumors. 5.Hardness: breast cancer lumps are hard in texture, but cell-rich medullary carcinoma can be slightly soft, and individual can be cystic, such as cystic papillary carcinoma. A few lumps are surrounded by more fatty tissues and have a tender feeling when palpated. 6.Mobility: When the mass is small, the mobility is larger, but this activity is together with the surrounding tissues, which is different from the mobility of fibroadenoma. If the tumor invades the fascia of pectoralis major muscle, the mobility will be reduced. If the tumor involves the pectoralis major muscle, the activity will be lost. If the patient crosses her arms and raises her chest to make the pectoral muscle contract, it can be seen that both sides of the breast are obviously asymmetric. In advanced stage, breast cancer may invade the chest wall, then it is completely fixed, the lymph nodes around the tumor are invaded, the skin edema can be orange peel-like, which is called “orange peel sign”, and the nodes under the skin around the tumor are called “satellite nodes”. Among benign breast tumors, breast lumps are not uncommon, and the most common one is breast fibroadenoma. The disease is more common in young women and has a low incidence over the age of 40. The tumor is often solid, tough, with an intact envelope, smooth surface, and a sliding sensation to the touch, usually without skin adhesions, and does not cause nipple retraction. In intraductal papilloma, the mass is often small and not easily palpable. In slightly larger cases, small nodules can be found around the areola, with nipple discharge as the main clinical symptom. Lobular hyperplasia rarely forms a clear lump, but is mainly a thickening of the local breast tissue, with a tough texture and no sense of envelope, often with swelling and pain before menstruation.