A patient with early stage mucinous breast cancer was admitted recently, which made me feel deeply. The patient’s left breast lump was about 2*2 cm in size, tough, mobile, well-defined and without adhesions to surrounding tissues. Therefore, early diagnosis and early treatment of breast lumps are very important. To achieve early diagnosis, patients need to raise their awareness. Early detection can be achieved by self-examination before symptoms appear. The key is to have the awareness of regular self-examination and to master the correct examination method. Once a breast lump is found, it is possible to seek medical attention in a timely manner, and the nature of the lump can be clarified by ultrasound, infrared, mammography and fine needle aspiration biopsy. If it is malignant, it should be removed surgically. Benign tumors can be followed up regularly if they are small, while large ones can be removed surgically. However, benign tumors also have the possibility of malignant transformation. Therefore, breast lumps should generally be removed surgically. Breast self-examination should be done at least once a month, preferably one week after menstruation. The correct method is: 1. Cross your hands to check both sides of the breast (left hand to check the right side, right hand to check the left side). 2, in addition to the thumb the remaining four fingers together, close to the chest wall, through each finger alternately light pressure, in order to touch the entire chest area. Also the examination is not limited to the elevated part of the breast. It is important to check the wider area up to near the collarbone, across to the armpits on both sides and between the left and right breast. Normal breasts are softer and feel something sliding under the fingers when there is a lump. 3, Do not use your hands to grasp and pinch the breast, because grasping and pinching will make the normal breast tissue shrink into a mass, which feels like a lump, even if there is really a lump in it, it is not possible to check.