Radiation Boost for Ductal Carcinoma In Situ After Whole Breast Radiation Therapy (WBRT) Improves Local Control: Analysis from Ten Pooled Academic Institutions

Authors: Moran, M.S. et al.

Source: Abstract presentation, Annual Society of Therapeutic Radiation Oncology 58th annual meeting September 2016

www.astro.org/News-and-Publications/News-and-Media-Center/News-Releases/2016/Radiation-boost-reduces-local-tumor-recurrence-for-DCIS-patients-following-WBRT/

It is standard practice to administer whole breast radiation following lumpectomy for invasive cancer.  It is also widely accepted that patients receiving these therapies also have a reduced risk of recurrence when the tumor bed receives a boost (supplemental dose) of radiation. It has been questioned if the same outcomes apply to cases of DCIS.

The investigators reviewed over 4,000 cases of DCIS from 10 institutions in the US, Canada and France. All patients had lumpectomies followed by whole breast radiation therapy (WBRT). Over 2,600 of these patients received a radiation boost and over 1,400 did not. They found that patients who received a boost had a reduction in ipsilateral (same side) local recurrence rates. Comparing boost and no boost, ipsilateral recurrence-free survival rates were 97.1% vs. 96.3% at five years, 94.1% vs. 92.5% at 10 years and 91.6% vs. 88% at 15 years. All of the values reached statistical significance. All age groups experienced the same benefits.

It was noted that some of the women had positive margins after lumpectomy, and these patients derived no benefit in recurrence reduction with boost therapy. However, the number of these patients was small and investigators suspect that a higher number of subjects would show the same reduction in recurrence risk.

The researchers summarize that, for women with DCIS treated with lumpectomy and WBRT and a life expectancy of at least 10 years, consideration should be given to boost therapy to reduce the risk of ipsilateral disease recurrence.