In a 10-year study conducted by the Institute of Cancer Research, researchers have found that a lower total dose of radiotherapy delivered in fewer large doses is as safe as other treatment courses for breast cancer, which typically deliver multiple small doses.

Earlier results of the FAST trial, which was launched in 2004, found that reducing the number of radiotherapy fractions to 5 was feasible and safe in the short term. The new results established the long-term safety of the regimen.

“After undergoing surgery to remove breast cancer, patients usually undergo weeks of radiotherapy,” said study co-author Judith Bliss, MSc, in a statement. “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.”

The study included 915 women from 19 centers across the UK, all of whom had early-stage breast cancer. Participants were assigned to 1 of 3 different courses of radiotherapy following breast cancer surgery. One regimen consisted of daily doses, while 2 regimens delivered 5 larger doses once a week. After completing the regimens, the women were assessed annually for up to 10 years to investigate adverse effects (AEs) to healthy breast tissue, including hardening of the breast, swelling, skin reactions, and changes in breast size.

“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,” Bliss said.

Moderate or severe long-term AEs were low across all 3 treatment groups, and the most common AE was breast shrinkage. The investigators observed no changes or minor changes in healthy breast tissue in 86% of all participants at the 10-year point.

The findings also support treatment options that are more convenient for patients who cannot tolerate long courses of daily radiation, according to the press release. Chief investigator John Yarnold, FRCR, said in a statement that the findings are likely to become a UK standard for patients with early phase breast cancer.

“People are increasingly living longer with their cancer thanks to smarter, kinder treatments, so establishing long-lasting safety of treatments is of utmost importance in order to help them live well with the condition,” Yarnold said in a press release.

REFERENCE
Long-term safety of radiotherapy in fewer doses for patients with early breast cancer demonstrated in 10-year study [news release]. Institute of Cancer Research; July 14, 2020. https://www.icr.ac.uk/news-archive/long-term-safety-of-radiotherapy-in-fewer-doses-for-patients-with-early-breast-cancer-demonstrated-in-10-year-study. Accessed July 23, 2020.