BARCELONA, Spain — Active breath control during radiotherapy for left-sided breast cancer reduced radiation exposure to the heart and the left anterior descending (LAD) artery compared with free breathing, according to findings presented at the 15th European Breast Cancer Conference. This benefit was observed across all three fractionation schedules evaluated in the ongoing BRAVE-HEART study.

These findings suggest “a strong clinical impact,” with model-based estimates indicating a reduction in predicted cardiac mortality risk, reported lead author Elisabetta Bonzano, MD, PhD, during a poster spotlight session at the conference.

“Cardiac exposure during left-sided breast cancer radiotherapy remains a key determinant of long-term morbidity and mortality,” said Bonzano, a radiation oncologist at Fondazione IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico) Policlinico San Matteo, Pavia, Italy.

Minimizing radiation exposure to the heart and surrounding structures remains an important goal of treatment. The BRAVE-HEART trial aimed to assess the cardiac-sparing effect of deep inspiration breath hold vs free breathing. Bonzano and colleagues studied 400 patients with early or locally advanced left-sided breast cancer who had radiotherapy at one of three fractionation schedules: 26 Gy in 5 fractions, 40 Gy in 15 fractions, or 50 Gy in 25 fractions with or without a simultaneous integration boost. The radiotherapy was delivered using three-dimensional conformal radiotherapy or intensity-modulated/volumetric modulated arc therapy techniques.

Dosimetric parameters, including the mean and maximum dose delivered to the heart and the LAD artery, were calculated. Breath hold performance was recorded to evaluate the feasibility of the active breath control method vs free breathing.

In the 26 Gy/5 fraction group, the mean radiation dose to the heart was significantly lower with active breath control vs free breathing (0.75 Gy vs 1.13 Gy; P < .001), with similar reductions in the LAD artery (1.98 vs 3.19 Gy).

In the 50 Gy/25 fraction group, the heart and the LAD artery were exposed to significantly less mean radiation with active breath control vs free breathing (2.60 vs 4.48 Gy for the heart; 4.06 vs 6.99 Gy for the LAD artery). The maximum dose recorded for the heart and LAD artery was also significantly lower in the active breath control vs free breathing groups (18.0 vs 26.9 Gy for the heart; 10.1 vs 16.0 Gy for the LAD artery).

Similar patterns were observed in the 40 Gy/15 fraction group. When free breathing and active breath control were compared in the same patient, the latter resulted in significantly greater reductions in radiation dose to both the heart and LAD artery, Bonzano said.

A model-based estimation suggested that predicted cardiac mortality risk was halved with the Active Breathing Coordinator (0.04 vs 0.08). The mean breath-hold duration was 25 seconds, and breath-hold metrics indicated high feasibility, including among older patients (mean age, 75 years).

Icro Meattini, MD, who was not involved in the research, noted caveats to this approach to cardiac dose reduction.

Active breath control was somewhat “time consuming,” Meattini explained, because it requires patients to learn how to hold their breath in a particular manner during their radiation treatment, which may be difficult for some patients.

One solution is to provide training sessions for patients undergoing the technique, an approach being implemented at Meattini’s hospital where patients are invited to weekly training sessions to perform active breath control, he said. There is also a shift toward other methods for reducing radiation dose to the heart, Meattini noted.

Bonzano explained, however, that the active breath control technique was feasible, even in older patients.

“Our aim is to move it toward a more personalized approach [and better] understand the patients who benefit the most from this technique,” Bonzano said.

This study was independently supported. Bonzano and Meattini reported having no relevant financial relationships.

Sara Freeman is a medical journalist based in London, England.