Surgical excision without whole breast irradiation for complete resection of ductal carcinoma in situ identified using strict, unified criteria

- Complete resection was defined with unified criteria in a single institution.
- With complete resection, ipsilateral breast cancer can be limited.
- Ipsilateral and contralateral breast cancer rates were 10.8% and 9.1%.
- The ipsilateral invasive cancer rate was 3.6%; no patient died of breast cancer.

BackgroundThe definition of complete resection of ductal carcinoma in situ (DCIS) is difficult to standardize because of the high variety of surgical breast conserving procedures, specimen handling, and pathological examinations. Using strictly controlled criteria in a single institute, the present study aimed to determine the ipsilateral breast cancer rate when radiotherapy is omitted following complete resection of DCIS.MethodsWe retrospectively examined 363 consecutive DCIS patients who underwent breast-conserving surgery, and of these, 125 (34.4%) had complete resection according to the criteria. We finally included 103 patients who omitted radiotherapy. Ipsilateral and contralateral breast cancer events were assessed.ResultsThe median follow-up period was 118 months. The incidences of ipsilateral and contralateral breast cancer and ipsilateral invasive breast cancer at 10 years were 10.8%, 9.1%, and 3.6%, respectively. No patient died of breast cancer.ConclusionIf complete resection of DCIS can be ensured, the annual incidence of ipsilateral breast cancer, even without irradiation, can be limited to approximately 1%, which equals the incidence of contralateral breast cancer.