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

J Clin Oncol. 2020 Dec 10;38(35):4175-4183. doi: 10.1200/JCO.20.00650. Epub 2020 Aug 24.


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.

Trial registration: NCT02104895.

Publication types

  • Clinical Trial, Phase III
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Breast Neoplasms / radiotherapy*
  • Female
  • Follow-Up Studies
  • Humans
  • Kaplan-Meier Estimate
  • Middle Aged
  • Patient Satisfaction
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy, Intensity-Modulated / adverse effects
  • Radiotherapy, Intensity-Modulated / methods
  • Survival Rate

Associated data