In cities, breast cancer has become the most common malignant tumor among women and breast cancer has become the number 1 killer that endangers the lives of Chinese women. Therefore, the prevention of breast cancer is extremely important. Because we cannot change our own genes, prevention of the cause of breast cancer is difficult to achieve; the principle of breast cancer treatment is early detection, early diagnosis and early treatment. Breast cancer in situ can be cured, and the prognosis of early stage breast cancer is much better than late stage breast cancer, so the detection of breast cancer through early stage is an effective way to prolong the survival time of breast cancer. To prevent breast cancer, we must first understand how to conduct breast examinations, which requires every woman to understand the following 4 basic examinations: 1. Monthly self-examination Every woman should do self-examination on the 5th-7th day of her monthly menstruation. Regular breast self-examination is an effective method for early detection of breast cancer, but the condition is that women should master to examine their own breasts correctly so as to find lesions and seek medical attention in time. Self-examination of the breasts should be done in a lying position, using the fingers of the middle three fingers to touch the breast in a circular motion in the direction of the vertical strip, with different pressure in each area. Hint: Many patients can’t feel breast cancer in the early stage, so it is more important to go to hospital for regular examination instead of relying on self-examination. 2. Doctor’s palpation Breast doctors are very experienced and more accurate in determining the presence of lumps by touch. In the 1960s, when the health insurance program was first implemented in New York City, most breast cancers were detected by breast specialists. After 10 years of the program’s trial the breast cancer death rate dropped by 29%. 3. Ultrasound When a physician suspects a lump in the breast, he or she must do a breast ultrasound, which can be used to determine the nature of the lump. It can be used to determine the lump’s growth rate and whether it needs timely surgery. Breast ultrasound has the following advantages: (1) no radiation damage, which is more suitable for young women; (2) it has obvious advantages in identifying solid and cystic lumps, and ultrasound can detect cysts of 2mm in diameter; (3) it can assist mammogram in screening dense breast; (4) accurate positioning, showing clear levels of the breast; (5) it can detect axillary and supraclavicular lymph nodes; (6) ultrasound has the ability to detect lymph nodes in the axilla and supraclavicular lymph nodes. (6) ultrasound examination is economical, simple, painless and non-invasive. Mammography is by far the most important and effective means to detect early breast tumors, and can detect clinically occult breast cancer and microscopic cancer: a foreign study showed that among 300 cases of breast cancer with “negative” clinical findings, 28% were in situ cancer, 7% had tumors <5mm in diameter, and only 2 were in situ cancer. It is generally believed that mammography screening detects breast cancer 2.5-3 years earlier than clinical screening. Tip: It is recommended that women after the age of 40, or women with high risk factors (such as family history of breast cancer, in situ breast cancer, etc.) should have regular annual mammograms.