Accelerated partial breast irradiation effectively prevents recurrence in early breast cancer
SAN ANTONIO — Accelerated partial breast irradiation after surgery appeared as effective as whole breast irradiation for preventing recurrence among patients with early breast cancer, according to 10-year follow-up results from the randomized phase 3 APBI IMRT Florence trial presented at San Antonio Breast Cancer Symposium.
The findings suggest that the less invasive partial breast procedure could be a reasonable alternative to whole breast irradiation.
“This research is a small piece of the puzzle,” Icro Meattini, MD, clinical oncologist in the radiation oncology unit at University of Florence in Italy, told Healio. “However, this trial does add robust evidence in favor of accelerated partial breast irradiation over whole breast irradiation. There is a reduction in overall treatment time, improvements in outcomes and an increase in the quality of life among patients who underwent accelerated partial breast irradiation.”
The trial included 520 women aged older than 40 years (median age, 62.8 years) with stage I or stage II breast cancer (maximum tumor size, 25 mm).
Researchers randomly assigned half of the women to accelerated partial breast irradiation, which consisted of a total 30 Gray of radiation to the tumor bed in five daily fractions. The other half of women received whole breast irradiation, which consisted of a total of 50 Gray administered in 25 daily fractions to the whole breast, plus a 10-Gray boost to the tumor bed in five daily fractions.
Most patients had hormone receptor-positive, HER2-negative breast cancer, and the majority were aged older than 50 years. The treatment groups were well-balanced with regard to age, tumor type, tumor size and adjuvant endocrine treatment.
An analysis performed after 5 years of follow-up showed no significant differences in ipsilateral tumor recurrence and OS between the two approaches.
The updated results were based on median follow-up of 10 years in both groups.
Results showed no statistically significant differences between women assigned accelerated partial breast irradiation and those assigned whole breast irradiation with regard to breast cancer recurrence (3.3% vs. 2.6%), OS (92.7% vs. 93.3%), breast cancer-specific survival (97.6% vs. 97.5%) or distant metastasis-free survival (96.9% vs. 96.9%).
Ten-year cumulative incidence estimates of locoregional recurrence were 3.9% (95% CI, 2.24-5.56) with accelerated partial breast irradiation vs. 3% (95% CI, 1.53-4.47) with whole breast irradiation. The difference did not reach statistical significance.
The differences in contralateral breast cancers (0.9% vs. 3.5%) and deaths (7.3% vs. 6.7%) between the accelerated partial breast irradiation and whole breast irradiation groups also failed to reach statistical significance.
The study’s relatively small sample size served as the primary limitation, Meattini said.
Still, these findings may help clinicals become more comfortable recommending accelerated partial breast irradiation for patients with lower risk for recurrence.
The once-daily regimen does not appear to compromise outcomes, and it also may produce an improved quality of life and minimize toxicity while reducing treatment time and costs, he said.
“We have not been able to identify a group of patients for whom we can safely omit radiation, but we can safely stratify patients according to individual disease biology,” Meattini told Healio. “Also, for partial breast irradiation, we should focus on dissection before irradiation, because this is where the future is headed.” – by Jennifer Southall
Meattini I, et al. Abstract GS4-06. Presented at: San Antonio Breast Cancer Symposium; Dec. 10-14, 2019; San Antonio.
Disclosure: The Radiation Oncology Unit of Florence University Hospital supported the study. Meattini reports no relevant financial disclosures. Please see the abstract for all other authors’ relevant financial disclosures.