Direct signs (1) Lumps Lumps are the direct signs of breast cancer and the main diagnostic basis of breast cancer. The size of the lump varies, and the size of the lump on X-ray is usually smaller than the clinical palpation, which is one of the signs of malignancy. Skin edema, peri-cancerous inflammation and infiltration of the cancer into the surrounding area are the main reasons why the lump is often larger on clinical palpation than on X-ray. The density of the mass is in most cases dense, similar to or slightly higher than the adjacent breast parenchyma. The morphology is mostly round, nodular, lobulated, or irregular. Most masses have indistinct margins and blurred borders, with slight and obvious burrs or infiltrates. Sometimes the contours may be partly clear and partly blurred. The length of the burr varies, and can be several centimeters long or shorter and brush-like. They can be caused by the fibroblastic reaction of the tumor or by the outward infiltration of the tumor along the mesenchyme. (2) Microcalcifications, which occupy a particularly important position in the diagnosis of breast cancer, are mostly seen in intraductal carcinoma and invasive ductal carcinoma. As a major sign of breast cancer, it not only helps to confirm the diagnosis of breast cancer, but in a significant number of cases, calcification is the only positive basis for the diagnosis of breast cancer. The typical malignant calcifications are found in clusters of different sizes, numbers, and shapes, and it is important to be alert if more than 5 microcalcifications ≤0.5 mm are seen within 1 cm2 on x-ray. The morphology of malignant calcifications varies and is often fine grained, fine linear, striated, bifurcated, irregularly polygonal or branched. Calcifications may accumulate within or around the mass, or they may be segmental or diffuse. Calcifications in fibroadenomas are often coarser, less numerous, and located within the tumor. Cysts and fat necrosis are often eggshell-like calcifications. Calcifications associated with secretory disease of breast ducts are spark-like or small rod-shaped calcifications. (3) Limited dense infiltrate When an abnormally high density is found in one area of the breast, or an asymmetrical dense area is found in both mammary glands, it is a limited dense infiltrate. (4) Distortion of local findings On X-ray, the normal contour of the breast parenchyma is altered and the interstitial components produce angular, stellate and burr-like changes. Indirect signs (1) Nipple and skin changes Nipple depression and skin thickening are the indirect signs of breast cancer. (2) Vascular abnormalities Due to the increase of blood flow, thickening of blood vessels can be seen in breast cancer. (3) Dilation and interruption of breast ducts 3. Ductography If there is nipple overflow, then ductography is feasible. Breast cancer ductography shows disorganized, uneven thickness, twisted or interrupted ducts, irregular walls, and filling defects. Multiple intraductal papillomas can also be seen as hematochezia, and ductography may show dilated ducts with multiple small filling defects. Breast cancer screening Screening is the early detection of abnormalities in asymptomatic people through certain tests, so that further tests can be performed to obtain early diagnosis and early treatment. Mammography has been shown to be the only means of detecting malignant tumors early and reducing mortality through the use of imaging.