Recently, the rates of early stage breast cancers involving breast-conserving therapy have increased due to use of mammography screening. Morever, a patient's desire to keep the breast is now considered to be a factor which determines the surgery tactics. However, there has been so far no consensus on optimal extent of surgery capable of preventing local recurrence. In order to precisely estimate such risk it is essential to take into account factors such as tumor size, surgical margin status and age. Besides, correlations between certain subtypes of breast cancer and various associated risks of local recurrence are to be established. Another important factor is to devise the necessary subsequent radiotherapy.