SAN DIEGO – , according to a new prospective, randomized study.
Side effects and physical well-being scores were similar among 400 women who received the two treatment regimens, and outcomes were similar or slightly better in the higher-dose group, reported Rinaa Punglia, MD, MPH, an associate professor of radiation oncology at Dana-Farber Brigham Cancer Center in Boston and colleagues at the annual meeting of the American Society for Radiation Oncology. In a press statement, Dr. Punglia noted that the outcomes weren’t as impressive as researchers had hoped, but it’s positive that higher doses didn’t cause more side effects.
The use of the higher-dose approach, known as hypofractionation, “resulted in fewer treatment breaks and less financial toxicity” vs. conventional fractionation, Dr. Punglia said at a news briefing. The findings of the FABREC study “support the use of hypofractionated postmastectomy radiation for patients with basic reconstruction.”
According to Dr. Punglia, “postmastectomy radiation therapy is indicated for almost one-third of mastectomy patients and improves the lives of patients who are at an elevated risk for recurrence.” However, “the addition of radiation therapy greatly increases the risk of reconstruction complications.”
The typical radiation treatment period is 5-6 weeks in these patients, a major hardship for patients that can take them away from their families for extended periods of time. The researchers sought to understand whether another approach – hypofractionation over 3-4 weeks – is a better option. The strategy is widely used after breast-conserving surgery, she said, and has been linked to similar cancer outcomes, improved quality of life, and improved breast appearance.
From 2018 to 2021, the researchers recruited 400 patients with stage 0-III breast cancer who were treated with mastectomy and immediately underwent implant-based reconstruction (median age = 47.0, 23-79). None had tumors growing into the chest wall or skin.
The patients, spread nationwide across 16 institutions, were randomized to receive conventional fractionation (n = 201, 25 fractions, 5 days a week for 5 weeks of 200 cGy) or hypofractionation (n=199, 16 fractions, 5 days a week, for about 3 weeks of 266 cGy).
The researchers tracked 385 patients over a median follow-up of 40.4 months. There was no statistically significant difference in distant recurrence (12 in conventional fractionation arm, 11 in hypofractionation arm), death (2 in each arm), local recurrence (1 in each arm), or toxicity in the chest wall area (20 in conventional fractionation arm, 19 in hypofractionation arm). Changes in physical well-being scores, the primary endpoint, were similar after controlling for age.
“We found that younger patients randomized to hypofractionation were less bothered by side effects of treatment at 6 months relative to their counterparts who received conventional fractionation,” Dr. Punglia said.
Treatment breaks were more common in the conventional fractionation arm (7.7%, mean = 3.3 days) vs. the hypofractionation arm (2.7%, mean = 2.8 days, P = .03).
Among 51 patients who took unpaid time off work, those who underwent hypofractionation took fewer mean days off (73.7 days vs. 125.8 days for conventional fractionation, P = .046).
The study is the first of its kind to compare conventional fractionation to hypofractionation in this population in a randomized, phase III study, Dr. Punglia said.
At the news briefing, an independent expert – Lori Pierce, MD, a professor of radiation oncology at the University of Michigan – said the new study is a “game changer.”
The findings about the benefits of hypofractionation “will potentially impact thousands of women,” said Dr. Pierce, former president of the American Society of Clinical Oncology. The shorter course of radiation is more convenient for patients, she said, and reduces hardship.
“Without a doubt, these results should be discussed with all patients who have had mastectomy and implant-based reconstruction,” she said.
In an interview, Bruce G. Haffty, MD, MS, professor and chair of Radiation Oncology at Rutgers Cancer Institute of New Jersey, said the study adds to existing data suggesting that shorter courses of therapy “are probably OK.” The new findings “give people a little more confidence that [short courses are] safe in terms of well-being and toxicity.”
However, the follow-up in the trial is relatively short, he said, and longer-term research will be needed to change the standard of care in these patients. “It’ll be an evolving story over the next 5-10 years,” he said.
The study was funded by the Patient-Centered Outcomes Research Institute. Dr. Punglia has no disclosures; disclosures for other authors were not provided. Disclosure information for Dr. Pierce was not provided. Dr. Haffty is an investigator in a similar study called RT CHARM.