Breast-Conserving Treatment With Partial or Whole Breast Irradiation for Low-Risk Invasive Breast Carcinoma—5-Year Results of a Randomized Trial

To report the 5-year results of a randomized study comparing the survival and cosmetic results of breast-conserving treatment with partial breast irradiation (PBI) or conventional whole breast irradiation (WBI).

Between 1998 and 2004, 258 selected patients with T1 N0–1mi, Grade 1–2, nonlobular breast cancer without presence of extensive intraductal component and resected with negative margins were randomized after breast-conserving surgery to receive 50 Gy/25 fractions WBI (n = 130) or PBI (n = 128). The latter consisted of either 7 × 5.2 Gy high-dose-rate (HDR) multicatheter brachytherapy (BT; n = 88) or 50 Gy/25 fractions electron beam (EB) irradiation (n = 40).

At a median follow-up of 66 months, the 5-year actuarial rate of local recurrence was 4.7% and 3.4% in the PBI and WBI arms, respectively (p = 0.50). There was no significant difference in the 5-year probability of overall survival (94.6% vs. 91.8%), cancer-specific survival (98.3% vs. 96.0%), and disease-free survival (88.3% vs. 90.3%). The rate of excellent to good cosmetic result was 77.6% in the PBI group (81.2% after HDR BT; 70.0% after EB) and 62.9% in the control group (52.2% after telecobalt; 65.6% after 6–9-MV photons; pWBI/PBI = 0.009).

Partial breast irradiation using interstitial HDR implants or EB to deliver radiation to the tumor bed alone for a selected group of early-stage breast cancer patients produces 5-year results similar to those achieved with conventional WBI. Significantly better cosmetic outcome can be achieved with carefully designed HDR multicatheter implants compared with the outcome after WBI.