Breast self-examination (BSE) was first proposed by Adiair in 1933 as a tool for early detection of breast cancer, and was widely considered to have the advantages of being inexpensive, non-invasive, low risk, and self-administered. But two randomized controlled trials have shown that BSE does not work in reducing breast cancer mortality. Scientists believe that BSE is ineffective in saving lives. This has led to a major divide in attitudes toward BSE. But this does not mean that women should not have their breasts examined. We advocate more for women to raise their level of breast awareness. That is the purpose of the author’s science. Breastcancer.org continues to believe that BSE is a useful and meaningful screening method, especially in conjunction with a physical exam and mammogram by a physician. It is the author’s experience that most breast cancers are detected by self-examination based on the current distribution of medical resources and regional differences in economic levels in China. Therefore, it is recommended that women should have a monthly, routine breast self-examination. The breasts of adult women are affected by the action of estrogen and progesterone in the body 3-4 days before menstruation, resulting in interlobular edema and ductal-alveolar hyperplasia, breast swelling and pain until the onset of menstruation, when the hormone level drops rapidly and the breasts gradually recover. Therefore, it is recommended that premenopausal women should choose 7 to 14 days after the onset of menstruation for this procedure. This is also the best time for breast ultrasound and mammography. In postmenopausal middle-aged and older women, the time for self-examination is not limited because the influence of endocrine hormones is relatively weaker due to the decrease of estrogen in the body. Face the mirror, shoulders flat, hands naturally down, and observe your breasts. Compare the size and shape of both breasts for symmetry, normal skin, and any redness and ulcers. Observe whether the nipples are symmetrical bilaterally, whether they are retracted, whether there is any change in skin properties, and whether there is nipple discharge (you can observe whether there are blood spots or fluid contamination in your underwear). Then the upper fetal arm so that the lower part of the breast can be better observed. Finally, the hands will be pinched and force to make the pectoral muscles contract, which can make some hidden tiny areas more visible. A full mammogram is performed in the supine position with the examined upper limb raised above the head. Palpate with the index, middle and ring fingers of the examining hand. The amount of pressure used is not fixed and can increase depending on the amount of tissue in the area being examined. You can start with the nipple and touch in larger and larger circles until you reach the outer edge of the breast. You can also move your finger up and down vertically. Whether the examination is radial or concentric, clockwise or counterclockwise does not really matter, as long as the entire breast is examined in place. The examination extends up to the clavicle, down to the edge of the rib cage, medially to the parasternal bone, and laterally to the mid-axillary line. Note whether a visible lump can be palpated. It is also possible to examine with one hand while the other hand is immobilized. The examination can be performed in the same way when standing. If you find problems and questions, please consult your local breast specialist clinic promptly.