As reported in the Journal of Clinical Oncology by Icro Meattini, MD, and colleagues, 10-year follow-up of the Italian single-center APBI-IMRT-Florence trial showed no differences in ipsilateral recurrence or survival with accelerated partial-breast irradiation vs whole-breast irradiation after breast-conserving surgery among women with early-stage breast cancer. Accelerated partial-breast irradiation was associated with less toxicity and better cosmesis outcomes.

Outcomes at 5 years showed no significant differences between accelerated partial-breast irradiation and whole-breast irradiation in ipsilateral recurrence (the primary endpoint) or survival rates at 5 years, with significantly improved treatment-related toxicity and cosmetic results in the accelerated partial-breast irradiation group.

Icro Meattini, MD

Study Details

In the trial, 520 patients from the Radiation Oncology Unit of the University of Florence were randomly assigned between 2005 and 2013 to receive external-beam intensity-modulated radiation therapy (IMRT) with accelerated partial-breast irradiation at 30 Gy in 5 once-daily fractions (n = 260) or whole-breast irradiation at 50 Gy in 25 fractions with a tumor bed boost of 10 Gy in 5 fractions (n = 260). More than 90% of patients were considered to be at low risk of recurrence.

Recurrence and Survival

Median follow-up was 10.7 years. The 10-year cumulative incidence of ipsilateral recurrence was 3.7% in the accelerated partial-breast irradiation group vs 2.5% in the whole-breast irradiation group (hazard ratio [HR] = 1.56, P = .40). At 10 years, overall survival was 91.9% vs 91.9% (HR = 0.95, P = .86) and breast cancer–specific survival was 97.8% vs 96.7% (HR = 0.65, P = .45).

For the accelerated partial-breast irradiation vs whole-breast irradiation groups, 10-year cumulative incidence rates were 3.7% vs 2.9% for locoregional recurrence (HR = 1.33, P = .58), 0.8% vs 3.2% for contralateral breast cancer (HR = 0.25, P = .08), and 2.9% vs 3.2% for distant metastasis (HR = 0.89, P = .83).

Toxicity and Cosmesis

The accelerated partial-breast irradiation group had significantly less acute (P = .0001) and late (P = .0001) treatment-related toxicity. The highest-grade acute toxicity was grade 1 in 19.1% and grade 2 in 2% of patients in the accelerated partial-breast irradiation group vs grade 1 in 28.8%, grade 2 in 31.2%, and grade 3 in 6.5% of patients in the whole-breast irradiation group. The highest-grade late toxicity was grade 1 in 4.5% of the accelerated partial-breast irradiation group vs grade 1 in 27.3% and grade 2 in 2.7% of the whole-breast irradiation group.

A greater proportion of patients in the whole-breast irradiation group had adverse (fair or poor) cosmesis outcomes as rated by both physicians (1.9% vs 0%, P = .0001) and patients (14.6% vs 0.8%, P = .0001).

The investigators concluded, “The 10-year cumulative ipsilateral breast tumor recurrence incidence in [patients with] early breast cancer treated with external accelerated partial-breast irradiation using IMRT technique in 5 once-daily fractions is low and not different from that after whole-breast irradiation. Acute and late treatment-related toxicity and cosmesis outcomes were significantly in favor of accelerated partial-breast irradiation.”

Dr. Meattini, of the University of Florence and Azienda Ospedaliero-Universitaria Careggi, Florence, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: For full disclosures of the study authors, visit ascopubs.org.