The most common manifestation of breast cancer precursors is breast lumps. Breast lumps may be the first sign of breast cancer patients, and many breast cancer patients find lumps in their breasts when they shower or change their clothes. However, it is not true that having breast lumps means breast cancer. About half of women may have breast lumps, which are related to the changes of estrogen in the body, but the majority of women have benign breast lumps, which may be breast enlargement or breast cysts, and most of such benign lumps occur in younger women. If breast lumps appear in women over 35 years old, they should be taken seriously, especially if they appear in post-menopausal women. There are many other precursors of breast cancer, such as orange peel-like changes in the skin of the breast; asymmetry of the two breasts or nipples, sunken nipples, upturned nipples, retracted nipples, or discharge; ulceration of the skin of the breast; reddening of the skin of the breast, rash-like inflammation; soreness and discomfort in the armpit, back of the shoulder, upper arm, etc., all of which may be precursors of breast cancer. Therefore, women must strengthen their awareness of breast self-protection, learn to self-examine and familiarize themselves with various breast cancer precursors, and seek medical attention as soon as they find any abnormalities in their breasts for early diagnosis and treatment in order to improve the cure rate of breast cancer.