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Accelerated partial breast irradiation reduces treatment time with favorable outcomes
Women with breast cancer who received accelerated partial breast irradiation after lumpectomy demonstrated favorable long-term outcomes and cosmesis, according to findings from a multi-institutional study.
Adjuvant radiotherapy following a lumpectomy — the standard of care option for women with breast cancer — can last up to 7 weeks and cause adverse effects. The current practice is to radiate the entire breast following a lumpectomy, which exposes both the lungs and the heart to radiation.
Mitchell Kamrava
Accelerated partial breast irradiation (APBI), a more targeted adjuvant radiation approach, delivers radiation to the cavity where the tumor was removed over the course of 1 week. About 15% of patients with breast cancer aged older than 66 years currently receive some form of APBI.
“Despite [a] clear improvement in outcomes, women continue to forgo radiotherapy as a result of logistics and/or reluctance to expose lung and heart tissue to radiation,” Mitchell Kamrava, MD, assistant professor of radiation oncology at UCLA Jonsson Comprehensive Cancer Center, and colleagues wrote. “Developing a more convenient treatment that does not compromise oncologic or cosmetic outcomes could improve rates of breast conservation for women.”
Kamrava and colleagues evaluated 10-year data on the use of multi-catheter APBI — the original method for delivering partial breast treatment — in 1,131 (median age, 59 years; range, 22-90) women who were treated with breast-conserving surgery and adjuvant APBI using multi-catheter brachytherapy between 1992 and 2013.
Most of the patients (73%) had invasive ductal carcinoma and 18% had ductal carcinoma in situ.
Mean follow-up was 6.9 years.
The 10-year actuarial risk of ipsilateral breast cancer recurrence was 7.6% (95% CI, 5.6-10.1). Other actuarial risks measured included regional failure (2.3%; 95% CI, 1.4-3.7), distant metastasis (3.8%; 2.5-5.7) and new contralateral cancers (4.6%; 95% CI, 3-6.9).
Additionally, cause-specific survival was 96.3% (95% CI, 94.2-97.6) and OS was 86.5% (95% CI, 83-89.3).
Results of a multivariable analysis indicated the only significant variables associated with an increased risk for local recurrence included high-grade disease (HR = 2.81; 95% CI, 1.2-6.58) and positive margin status (HR = 18.42; 95% CI, 4.73-71.67).
Among patients with more than 5 years of follow-up data, physicians reported excellent/good cosmesis outcomes in 84% of the patients (P = .05).
The broad selection criteria for the study resulted in a diverse cohort with varying histologies, large tumor sizes, varying ages, node-positive disease, ER-negative disease and positive margins. Thus, the results of the study showed positive outcomes for women who may have been classified as either “unsuitable” or “cautionary” for this treatment option, researchers noted.
However, the study is also limited by the length of time the study took place, a period during which several treatment advances occurred that have helped local control rates for breast cancer. “Whether or not APBI is equivalent to whole-breast radiation will ultimately be determined by the upcoming results of multiple ongoing trials,” the researchers wrote. “While we await the results of level 1 evidence, these data provide valuable information that 5-day APBI in appropriately selected women can be considered as an alternative to conventional 6- to 7-week external beam, whole-breast radiation.” – by Anthony SanFilippo
Disclosure: The researchers report no relevant financial disclosures.