During the menstrual cycle, due to the influence of various related endocrine hormones, the breast will undergo some physiological changes of hyperplasia and rejuvenation, causing the breast tissue to be in various degrees of congestion and edema, and these changes may interfere with the doctor’s examination of the location, size and nature of the breast lumps, thus affecting the judgment of the nature of the breast lumps. When is the most appropriate time to check for breast disease? The best time for breast examination is usually around the tenth day of menstruation, when estrogen has the least effect on the breast and the breast is in a relatively quiescent state, so breast lesions or abnormalities can be easily detected. Post-menopausal elderly women can choose the time to visit the doctor at will because their estrogen is reduced and they are less affected by endocrine hormones. Breast cancer is most prevalent between 45 and 55 years old, but there is a trend of younger age of incidence. If breast lesions are detected during self-examination or screening, you should seek early medical attention and follow up with your doctor. Some patients who are in clinical remission from benign breast disease do not have regular follow-up examinations for a long time, and when the original benign lesions become malignant, it will be very difficult to cure them. Therefore, early consultation should be an important principle, and choosing the best time for consultation is an important means to improve the correct diagnosis.