Inclusion Criteria:

- Eastern Cooperative Oncology Group performance score﹤2

- All patients aged >18 years and < 70 years after breast conserving surgery.

- On histological examination, the tumor must be DCIS or invasive adenocarcinoma of the
breast.

- Negative nodal status determined by sentinel node biopsy, or axillary dissection.
Axillary staging is not required for patients with DCIS

- No evidence of distant metastasis

- Gross disease may be unifocal or multifocal with pathologic (invasive and/or DCIS)
tumor size excised with negative margins（＞2mm）

- Surgical treatment of the breast must have been lumpectomy. Re-excision of surgical
margins is permitted.

- The patient must consent to be in the study and must have signed an approved consent
form.

Exclusion Criteria:

- Eastern Cooperative Oncology Group performance score≧2

- Presence of extensive intraductal component (ductal carcinoma in situ occupying > 25%
of the primary invasive tumour and present adjacent to the primary tumour).Suspicious
microcalcifications, densities, or palpable abnormalities (in the ipsilateral or
contralateral breast) unless biopsied and found to be benign.

- Proven multicentric carcinoma (invasive cancer or DCIS) in more than one quadrant of
separated.

- Metastatic disease (M1)

- Pregnancy or lactating

- Surgical margins that cannot be microscopically assessed or are positive at
pathologic evaluation.

- Psychiatric or addictive disorders that preclude obtaining informed consent or
adherence to protocol.

- Collagen vascular disease, specifically dermatomyositis with a CPK level above normal
or with an active skin rash, systemic lupus erythematosis, or scleroderma.

- Prior breast or thoracic RT for any condition.

- Previous or concomitant malignancies except non-melanoma skin cancer, carcinoma in
situ of the cervix, and invasive carcinoma of the colon, thyroid, cervix, or
endometrium treated five years prior to study entry.

- Synchronous chemotherapy or target therapy is not permitted.

- Refusal of the patients to be included in the study