A complete medical history is crucial to the diagnosis of breast cancer. The following aspects should be carefully inquired about the patient’s condition: 1. 2.Whether there is nipple erosion and overflow, the color nature of the fluid, the amount, intermittent or continuous. 3. Whether tests and treatments have been done and what the results are. For example, whether pathological examination, estrogen and progesterone receptor status, whether chemoradiotherapy or endocrine therapy has been done. 4. Any previous history of breast inflammation, trauma, proliferative disease, and benign or malignant tumors. 5. Menstruation, marriage and breastfeeding. 6. Any family history of tumor, especially any family history of breast cancer in the immediate family. Physical examination Observe the size, shape, curvature and symmetry of the contour of the breast, the color of the breast skin, the position of the nipple and whether there is erosion of the nipple skin. When palpation is performed, the healthy breast should be examined first, and then the affected breast should be examined. The whole breast should be touched gently with the palm of the finger flat on the chest in a sequential manner, with special attention to the nipple, areola and axillary tail of the breast. The axilla and clavicle should be carefully examined for enlarged lymph nodes. Imaging examination 1. Mammography Breast cancer can be divided into direct and indirect signs. The direct signs include limited mass, clusters of microcalcifications, limited dense infiltration, distortion of breast structure, asymmetry of breast structure on both sides, etc. The indirect signs include thickened or retracted skin, abnormal nipple and areola, peritumor edema, abnormal thickened blood vessels, etc. Ultrasound examination of breast is the most important basis for analysis of breast masses. The sonogram of breast cancer appears as hypoechoic nodules or masses, often with uneven echogenicity. The anteroposterior diameter of the mass is often larger than the transverse diameter, and the contour is irregular. When an irregular mass has a distinct acoustic shadow, it is likely to be breast cancer. 3.Magnetic resonance examination of breast Magnetic resonance examination of breast is suitable for the following cases: to determine the scope of breast cancer; mammogram X-ray shows dense breast tissue and needs to clarify whether there is a multicentric lesion; to understand the scope of disease in patients with locally advanced breast cancer. The following points should be noted regarding MRI: ①MRI cannot replace standard mammography and ultrasound examination of the breast and corresponding drainage area. For patients with biopsy-confirmed adenocarcinoma of the axillary lymph nodes, but with normal clinical breast physical examination and negative mammogram, MRI should be performed to detect the primary breast lesion. For patients with biopsy-confirmed breast cancer, if the breast tissue is so dense that the extent of the disease cannot be assessed, MRI can be considered. 4.CT presentation of breast cancer Direct sign: limited mass is the main CT presentation of breast cancer. CT is not as good as X-rays in showing microcalcifications. The enhancement of breast cancer is higher than the surrounding normal glands, and the masses are more clearly shown than on plain scan. Indirect signs: skin thickening, subcutaneous tissue or pre-pectoral fatty tissue reticular changes, invasion of pectoral muscle, nipple and areola changes and thickening of large ducts are superior to radiographs. Lymph node metastasis: CT can show axillary lymph nodes and internal breast lymph node metastasis, which is superior to X-ray film and ultrasound scan in this aspect. Tumor markers The tumor markers associated with breast cancer are CEA, CA153, CA125 and TPS. 71% of breast cancer patients have elevated serum CEA, but elevated CEA is also seen in gastrointestinal tumors, lung cancer, cardiovascular disease and benign liver lesions, so the specificity is poor. About 73% of patients have elevated CA153, and about 5% of normal individuals also have false positives. Therefore, the combined test of CEA and CA153 is more helpful in determining the recurrence and prognosis of breast cancer. The elevated level of TPS (tissue peptide specific antigen) in the serum of patients with metastatic breast cancer is more significant than that of CA153, and about 85% of patients are accompanied by elevated TPS. elevated CA125 is seen in ovarian cancer, pancreatic cancer and other tumors, and the serum positivity rate of breast cancer patients is about 20%. For patients with confirmed invasive breast cancer, HER-2 status should be detected. Fluorescence in situ hybridization or immunohistochemistry can be used. If HER-2 gene amplification is confirmed by fluorescence in situ hybridization or immunohistochemistry result ++++, it is defined as HER-2 positive for breast cancer. Both methods, fluorescence in situ hybridization or immunohistochemistry, may result in false positives or false negatives, so it is advisable to validate the test results. the HER-2 test report should include the following information: tumor site, specimen type, histological type, specimen fixation method and time, wax block tested, and HER-2 detection method. HER-2 status not only determines whether a patient with invasive breast cancer can receive a trastuzumab-containing regimen, but also contributes to the choice of treatment options and the determination of prognosis. For example, HER-2-positive patients are better treated with anthracycline-based chemotherapy regimens than non-anthracycline-based regimens, and the dose of doxorubicin is critical to the treatment of HER-2-positive breast cancer.