Researchers have found that a low-dose radiotherapy boost in addition to whole-breast radiotherapy may prevent local recurrence in young patients with breast cancer, according to new findings presented by Bosma et al at the 2024 European Breast Cancer Conference (EBCC) (Abstract 4LBA) and simultaneously published in the European Journal of Cancer.
Background
“Young [patients with] breast cancer generally have a worse prognosis than older patients. [Nonetheless], because breast cancer is more common in older women, younger women are underrepresented in most breast cancer studies,” explained lead study author Sophie Bosma, MD, PhD, a radiation oncologist at the Netherlands Cancer Institute in Amsterdam. “We know that in young patients there is a higher chance of the breast cancer returning in the same place following breast-conserving treatment. In this trial, we were aiming to lower that risk by giving patients a high radiotherapy boost directed at the site of the tumor. We were also comparing a higher and lower dose to see which one worked best for young patients in terms of local control and cosmetic outcome,” she added.
Study Methods and Results
In the new trial, the researchers recruited 2,421 patients aged 50 years and younger who had breast cancer and were treated at 32 centers across the Netherlands, France, and Germany. Following treatment with surgical resection and whole-breast radiotherapy, the patients were randomly assigned to receive either a low-dose (16 Gy) or high-dose (26 Gy) radiotherapy boost. The majority of the patients also received chemotherapy.
After an average follow-up of 11 to 12 years, they found that 109 of the patients experienced cancer recurrence in the same breast. The patients in the low-dose group had a 10-year local recurrence rate of 4.4% (n = 61) vs 2.8% (n = 48) in the high-dose group. However, 48% of the patients who received the high-dose radiotherapy boost experienced severe or moderate fibrosis in the breast compared with 27% of the patients who received the low-dose radiotherapy boost—indicating that the lower risk of local recurrence may not justify the increased impact on cosmetic outcomes.
Conclusions
“In both groups, local recurrence rates were very low and much better than expected. Although we did find a difference between the two groups in terms of the recurrence rate, this was a small difference [that] must be weighed against the increase in side effects such as fibrosis. Knowing the long-term impact of a treatment on cancer control as well as on unwanted side effects is crucial in helping individual patients get the best possible treatment,” underscored Dr. Bosma.
“Radiotherapy plays an important role in breast cancer treatment, especially in young women where there is a higher risk of the breast cancer returning. This important study provides critical information for the optimal boost radiotherapy dose for achieving local control without compromising the cosmetic outcome,” concluded Michail Ignatiadis, MD, PhD, of the Institut Jules Bordet in Brussels and Chair of the 2024 EBCC, who was not involved in the research.
Disclosure: The research in this trial was supported by the Dutch Cancer Society, the French Ministry of Health, and a Pink Ribbon grant. For full disclosures of the study authors, visit ejcancer.com.
