The investigators will perform this study to prospectively analyse the clinical outcome after percutaneous microwave ablation(MWA) of benign and malignant breast lesion under ultrasound (US) guidance.

A total of more than 500 patients diagnosed with benign breast lesions and 50 patients with malignant breast lesions in seven centers of China will be recruited in this study and underwent US-guided percutaneous MWA treatment. Information for each patient includes demographics; longest diameters of tumors; tumor numbers; tumor pathological type; location of tumor according to whether adjacent to skin, pectoralis, areola and papilla. Ablation variables including session, puncture, time, and power; complete ablation, complications; reduction in volume, palpability, pain and cosmetic satisfying outcomes,recurrence,survival will be measured and analyzed.

Inclusion Criteria:

• breast lesion proved by using core-needle biopsy;
• for benign lesions,lesion 1.0 cm or larger in greatest diameter and continually increasing during a half year follow-up; for malignant ones, lesion size 2cm or smaller;
• distance of at least 1.0cm to papilla with the patients supine;
• the symptoms of local pain, discomfortable or compression considered probably relating to the lesion of breast;
• the patient with evidently psychological pressure due to the occurrence of the lesion;
• patients unwilling or refused to receive other treatment and presence of an appropriate route for percutaneous puncture under US guidance.

Exclusion Criteria:

• patients who were pregnant or breast-feeding;
• patients with evidence of coagulopathy or acute or severe pulmonary insufficiency or heart dysfunction;
• patients during menstrual period;
• patients who wanted to undergo other therapies including surgical excision and vacuum-assisted biopsy.

cosmetics effect, volume reduction rate,complications