Treatment of breast cancer and precancerous lesions WANG Shu, ZHANG Jia-qing, CAO Ying-ming. Breast Disease Center, Peking University People?s Hospital, Beijing 100044, China Abstract Up to now, pathological diagnosis is the final decision for precancerous lesions, and surgery is the most effective management. There is a particular dilemma for surgeons, who must balance the risk of resecting too much and causing unnecessary cosmetic damage, or resecting too small and leaving an increased risk of recurrence. Ductal carcinoma in situ(DCIS) is the intermediate stage between precancerous lesions and invasive breast carcinoma, surgery, radiotherapy and risk reduction endocrinotherapy have become the main treatment for DCIS.