Compelling clinical trial evidence supports the use of hypofractionated radiation as the standard of care for postmenopausal women with luminal A tumors and node-negative disease.
Most women who receive radiation therapy following breast-conserving surgery would fare just as well in terms of recurrence rate and cosmetic outcome with a shorter course of treatment than is commonly given in the United States, but health system incentives help promote a longer and more expensive approach, according to a leading expert from The University of Texas MD Anderson Cancer Center.
Compelling clinical trial evidence supports the use of hypofractionated radiation as the standard of care for postmenopausal women with luminal A tumors and node-negative disease, said Thomas A. Buchholz, MD, executive vice president and physician-in-chief at the center in Houston, during a presentation at the Miami Breast Cancer Conference.
The regimen was defined in a landmark clinical trial in Canada as 42.5 Gy in 16 fractions over 22 days, in contrast with the traditional 50.0 Gy in 25 fractions over 35 days (N Engl J Med. 2010;363:513-520).
After 10 years, the risk of recurrence was 6.7% among women who received standard radiation versus 6.2% for participants who were administered the hypofractionated dose, for an absolute difference of 0.5% (95% CI; -2.5-3.5). The rate of good or excellent cosmesis also was similar at 71% for standard therapy versus 70% for the hypofractionated regimen.
Those results were supported by two British studies, the START A and B trials, involving more than 4400 patients. In the START B trial, a shorter radiation course resulted in lower rates of local recurrence (4.3% vs 5.5%) and distant relapse (12.3% vs 16.0%) compared with a longer regimen, Buchholtz said. He said the rate of any breast cancer event also was lower at 18.3% compared with 22.2%.
However, Buchholz said, the adoption of hypofractionation has been “pretty disappointing” in the United States, citing one study of a Medicare population that found only 20% of patients treated with breast conservation received hypofractionation in 2013.
He cited several reasons for the hesitancy to adopt hypofractionation, including the widespread availability of linear accelerators and other treatment resources, as well as physician and hospital payment systems that compensate care based on the number of treatments. “If you did a bundled payment, you’re going to see a rapid increase in the uptake of hypofractionation,” said Buchholz.
Buchholz also said newer technologies such as accelerated partial breast irradiation are attractive to US providers.
By contrast, physicians in Canada and the United Kingdom, where fewer technological resources helped drive the studies of shorter treatment courses, payment systems are different and physicians have adopted the new standard.
Overall, the data show that hypofractionation is appropriate across most subgroups, said Buchholz. He said the only group for whom that schedule is not recommended are patients with higher risk, high-grade (G3) tumors or triple-negative disease, which is more resistant to treatment, said Buchholz.
In 2011, the American Society for Radiation Oncology (ASTRO) found that a hypofractionated schedule was equivalent to the traditional regimen for patients aged ≥50 years or older with stage T1-T2N0 tumors who had been treated with breast conservation, Buchholtz said.
Two years later, ASTRO incorporated this advisory as part of its Choosing Wisely Campaign: “Don’t initiate whole breast radiotherapy as part of breast conservation therapy in women age ≥50 with early stage invasive breast cancer without considering shorter treatment schedules.”
“I think ASTRO has to make a stronger statement than that and say it should be the standard of care—because it really should be for these women,” said Buchholtz.