Whole-breast irradiation (WBI) plus regional nodal irradiation (RNI) significantly improved disease-free survival, but not overall survival, in a randomized, multicenter phase III trial of women with node-positive or high-risk node-negative disease who were treated with breast-conserving surgery and adjuvant therapy. An interim analysis of 1,832 women with breast cancer found that after a median follow-up of 62 months (between March 2000 and March 2007), WBI plus RNI significantly reduced the risk of locoregional recurrence from 5.5% to 3.2% (hazard ratio [HR], 0.58; P = 0.02) and distant recurrence from 13.0% to 7.6% (HR, 0.64; P = 0.002), according to the lead investigator, Dr. Timothy Whelan, head of radiation oncology at McMaster University and the Juravinski Cancer Centre, Hamilton, Ontario, Canada.
As a result, disease-free survival rate improved from 84.0% for WBI to 89.7% for WBI plus RNI (HR, 0.67; P = 0.003). Overall survival in the intergroup trial was 90.7% with WBI, compared with 92.3% with the combined radiation regimen, but the difference did not reach statistical significance (HR, 0.76; P = 0.07). In view of the positive findings from the National Cancer Institute of Canada Clinical Trials Group MA.20 study, the data safety monitoring committee recommended that the results be released. The data were presented by Dr. Whelan at the 2011 annual meeting of the American Society of Clinical Oncology (ASCO).1
Report prepared by Matt Stenger, MS
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