Results of EORTC trial 10853 appearing in the Journal of Clinical Oncology show that breast conserving treatment combined with radiotherapy reduces the risk of local recurrence in women with ductal carcinoma in situ (DCIS). The incidence of DCIS has been increasing in the past decades, and this has been attributed to increased detection through breast cancer screening using mammograms. In the EORTC study, adjuvant radiotherapy after local excision reduced the incidence of both in situ and invasive local recurrences by a factor of two and resulted in an overall lower risk of mastectomy.

Following the introduction of radiotherapy combined with breast-conserving surgery for operable invasive breast cancer in the 1980’s, several trials were launched to investigate the addition of radiotherapy to local excision of DCIS. These trials showed that radiotherapy reduced both the risk of DCIS and invasive local recurrences. Now the long-term outcomes of local recurrences and survival in women receiving radiotherapy in combination with breast conserving surgery for DCIS have been investigated at a median follow-up of 15.8 years.

Dr. Mila Donker of The Netherlands Cancer Institute, Amsterdam, and lead author of this paper says, “Survival after treatment for DCIS is excellent. Therefore, the question rises whether the current treatment for DCIS (local excision and adjuvant radiotherapy of the breast) is overtreatment. To answer this question, not only long-term data about local disease recurrences and prognosis are important, but also information about the prognosis and treatment in case of recurrence.”

Between 1986 and 1996, the phase III EORTC trial 10853 randomized 1010 women with complete local excision of DCIS to no further treatment (503 patients) or radiotherapy (507 patients). The risk of any local recurrence was found to be reduced by 48% (HR: 0.52, 95%CI 0.40-0.68, P

<0.001) in the patients who also received radiotherapy. The 15-year local recurrence-free rate was 69% for the group of patients receiving breast conserving surgery alone, but this increased to 82% for the group of patients who also received radiotherapy, and the 15-year invasive local recurrence-free rate was 84% versus 90%, respectively (HR: 0.61, 95%CI 0.42-0.87).

The differences observed in local recurrence did not lead to differences in breast cancer specific survival or overall survival, but patients with invasive local recurrence did have a significantly worse breast cancer specific survival (HR: 17.66, 95%CI 8.86–35.18) as well as overall survival (HR: 5.17, 95%CI 3.09-8.66) than those who did not recur. Thus, an invasive recurrence resulted in a worse prognosis.

A lower overall salvage mastectomy rate after a local recurrence was also observed in the group of patients who also received radiotherapy, 13%, than in those patients who just received breast conserving surgery, 19%. Thus, radiotherapy after breast-conserving surgery for DCIS resulted in an overall lower percentage of patients who were treated with a mastectomy after a local recurrence.

This study highlights the importance of conducting long term follow-up.

EORTC trial 10853 was coordinated by the EORTC Breast Cancer Group and conducted in 46 sites in 13 countries: The Netherlands, France, Italy, Belgium, United Kingdom, Portugal, Greece, Switzerland, Germany, South Africa, Austria, Israel, and Spain. It was a fully academic trial supported by EORTC Charitable Trust, Kankerbestrijding/KWF from The Netherlands.

John Bean, PhD
EORTC Medical Science Writer

###