Fewer Larger Doses of Radiotherapy Safe, Effective in the Long-run for Breast Cancer Patients

A 10-year study found that breast cancer patients receiving radiotherapy may have similar outcomes and side effects if they receive a few large doses of radiotherapy or a higher number of smaller doses, even if the former adds up to a lower total amount. The study may be promising for patients who cannot tolerate the side effects associated with daily radiation treatment.

“After undergoing surgery to remove breast cancer, patients usually undergo weeks of radiotherapy. The aim of the FAST trial was to figure out if using fewer fractions overall, with careful consideration of the total dose, would reduce the side effects observed, said co-leader of the study Professor Judith Bliss, MSc, professor of Clinical Trials at The Institute of Cancer Research, London, and director of its Cancer Research UK-funded Clinical Trials and Statistics Unit, in a press release. “Our initial results showed that when the total dose is adjusted appropriately it is safe to deliver radiotherapy in fewer doses and now we can confirm that this is still the case 10 years down the line.”

The study recruited women aged 50 years and older with low-risk invasive breast cancer between 2004 and 2007 from 18 centers in the UK. They were randomized to receive either the traditional treatment regimen of 25 daily doses of 2 Gy for five weeks, totaling 50 Gy, or the experimental treatment regimen, in which patients received 6 Gy or 5.7 Gy once a week for five weeks, totaling 30 Gy or 28.5 Gy. The main outcome measure was changes in photographic breast appearance at two and five years. Other outcomes included an assessment of normal tissue effects (NTE) and local tumor control.

Less Frequent Radiotherapy May Work for Some Patients

Among 915 women initially recruited, 862 were eligible for inclusion, of whom 615 had five-year photographs available. The odds ratio (OR) for changes in photographic breast appearance for women who received the 30 Gy regimen, compared to 50 Gy, was 1.64 (95% confidence interval [CI], 1.08 to 2.49; P=0.019); for the 28.5 Gy group, the OR was 1.10 (95% CI, 0.70 to 1.71; P=0.686). When comparing the 30 Gy group to the 50 Gy group, the OR for physician-assessed breast NTE was 2.12 (95% CI, 1.55 to 2.89; P<0.001), and for the 28.5 Gy group was 1.22 (95% CI, 0.87 to 1.72; P=0.248). After a median 9.9 years of follow-up, the researchers reported 11 ipsilateral breast cancer events (50 Gy, n=3; 30 Gy, n=4; 28.5 Gy, n=4) and 96 deaths (n=30, n=33,  and n=33, respectively).

The results were published in the Journal of Clinical Oncology.

“These findings have supported a change in clinical practice that is already helping relieve pressures on the NHS—and it is great to see that after so many years, side effects from fewer but larger doses of radiation are still low,” Professor Bliss said.