Accelerated Partial-Breast Irradiation Compared With Whole-Breast Irradiation for Early Breast Cancer: Long-Term Results of the Randomized Phase III APBI-IMRT-Florence Trial

Abstract

PURPOSE To report the long-term results of external-beam accelerated partial-breast irradiation (APBI) intensity-modulated radiation therapy (IMRT) Florence phase III trial comparing whole-breast irradiation (WBI) to APBI in early-stage breast cancer. PATIENTS AND METHODS The primary end point was to determine the 5-year difference in ipsilateral breast tumor recurrence (IBTR) between 30 Gy in 5 once-daily fractions (APBI arm) and 50 Gy in 25 fractions with a tumor bed boost (WBI arm) after breast-conserving surgery. RESULTS Five hundred twenty patients, more than 90% of whom had characteristics associated with low recurrence risk, were randomly assigned (WBI, n = 260; APBI, n = 260) between 2005 and 2013. Median follow-up was 10.7 years. The 10-year cumulative incidence of IBTR was 2.5% (n = 6) in the WBI and 3.7% (n = 9) in the APBI arm (hazard ratio [HR], 1.56; 95% CI, 0.55 to 4.37; P = .40). Overall survival at 10 years was 91.9% in both arms (HR, 0.95; 95% CI, 0.50 to 1.79; P = .86). Breast cancer–specific survival at 10 years was 96.7% in the WBI and 97.8% in the APBI arm (HR, 0.65; 95% CI, 0.21 to 1.99; P = .45). The APBI arm showed significantly less acute toxicity ( P = .0001) and late toxicity ( P = .0001) and improved cosmetic outcome as evaluated by both physician ( P = .0001) and patient ( P = .0001). CONCLUSION The 10-year cumulative IBTR incidence in early breast cancer treated with external APBI using IMRT technique in 5 once-daily fractions is low and not different from that after WBI. Acute and late treatment-related toxicity and cosmesis outcomes were significantly in favor of APBI.

The Acute and Late Toxicities of MRI-Guided External Beam Partial Breast Irradiation Delivered Using a Once-Per-Day Regimen

“…Regardless of the schedule, a twice-per-day regimen would be associated with significant biological effects caused by incomplete recovery. Meattini et al performed APBI at 30 Gy in 5 nonconsecutive once-daily fractions, at 48-h intervals, and reported favorable toxicity outcomes of APBI (22). We performed APBI using a once-per-day regimen, thus at 24-h intervals.…”

Improved Ipsilateral Breast and Chest Wall Sparing With MR-Guided 3-fraction Accelerated Partial Breast Irradiation: A Dosimetric Study Comparing MR-Linac and CT-Linac Plans

“…Stereotactic body radiation therapy (SBRT) and hypofractionated intensity modulated radiation therapy (IMRT) offer a unique approach for treating localized tumors with ablative doses of radiation, while sparing the surrounding organs-at-risk. Longterm results from a phase III study by University of Florence (7) and a recent phase I doseescalation study by Rahimi et.al. (8), support the use of a 5-fraction APBI regime.…”

The Case for Brachytherapy: Why It Deserves a Renaissance

“…Partial breast irradiation (PBI) has demonstrated comparable treatment outcomes to whole breast irradiation with regard to local tumor control, toxicity, and cosmetic outcomes. 29 , 30 , 31 , 32 , 33 Initially, accelerated PBI provided a method to shorten typical 5- to 6-week standard fractionation radiation courses to 5 days. The recent publication of the UK Fast Forward study offers an even faster external beam option for the delivery of radiation to the breast.…”