To report the 20-year results of a phase III clinical trial comparing the survival
and cosmetic results of breast-conserving surgery (BCS) followed by partial (PBI)
or whole breast irradiation (WBI).Between 1998 and 2004, 258 selected patients with
low-risk invasive breast carcinoma (pT1 pN0-1mi, Grade 1-2, non-lobular breast cancer)
resected with negative margins were randomized after BCS to receive PBI (n=128) or
50 Gy WBI (n=130). Partial breast irradiation was given either by multi-catheter high-dose-rate
(HDR) brachytherapy (BT; n=88) with 7 x 5.2 Gy b.i.d. or 50 Gy external beam irradiation
with electron beams (EB; n=40).Median follow-up time was 17 years. The 20-year actuarial
rates of ipsilateral breast tumor recurrences were 9.6% versus 7.9% (p=0.59) in PBI
and WBI arms, respectively. There was no significant difference in the 20-year probability
of disease-free (79.7% vs. 78.3%), cancer-specific (92.6% vs. 88.1%), and overall
survival (59.5% vs. 59.7%). Significantly more patients had excellent or good cosmetic
result in the PBI and WBI groups (79.2% vs 59.5%; p=0.0007).The 20-year updated results
of our phase III clinical trial add further scientific evidence that PBI either with
multi-catheter HDR BT or EB for low-risk invasive breast carcinomas yields comparable
long-term local tumor control and survival to those achieved with standard WBI. Interstitial
HDR BT significantly improved cosmetic results compared to WBI.
