Clinical Outcome Analysis in “High-Risk” Versus “Low-Risk” Patients Eligible For National Surgical Adjuvant Breast and Bowel B-39/Radiation Therapy Oncology Group 0413 Trial: Five-Year Results

Abstract

To report the local control and overall survival outcomes after lumpectomy followed by accelerated partial breast irradiation in high-risk patients as defined by the current inclusion criteria for the National Surgical Adjuvant Breast and Bowel B-39/Radiation Therapy Oncology Group 0413 Intergroup trial. Between 2000 and 2005, 273 women with early-stage breast cancer were treated using either multicatheter interstitial brachytherapy (n=247) or MammoSite (n=26). Patients received 32-34 Gy in 8-10 twice-daily fractions using high-dose-rate 192Ir brachytherapy. All patients met the initial inclusion criteria for the Intergroup trial and were separated into two groups: high-risk patients (representing the cohort that remained eligible for the Intergroup trial) who satisfied one or more of the "high-risk" criteria (age<50 years, estrogen receptor negative, and/or positive lymph nodes; n=90), and low-risk patients who comprised the remainder of the cohort (n=183). The outcomes of the two cohorts were analyzed and compared. The median follow-up of the entire cohort was 48.5 months. No significant difference was found in outcomes at 5 years between the low- and high-risk groups, with a local control rate of 97.8% vs. 93.6%, crude local recurrence rate of 2.2% (n=4) vs. 4.4% (n=4), and overall survival rate of 92.1% vs. 89.5%, respectively. At 5 years, no statistically significant difference was found in outcomes for patients deemed to be at greater risk in the current National Surgical Adjuvant Breast and Bowel B-39/Radiation Therapy Oncology Group 0413 Intergroup trial. These clinical data support the inclusion of this "high-risk" population in this important ongoing study.