Partial-breast radiation is a promising alternative to whole-breast radiation to many patients with breast cancer – especially if their disease is low-risk, according to research presented at the 2019 American Society of Clinical Oncology (ASCO) annual meeting
Administering post-lumpectomy partial-breast radiation can improve patients’ quality of life and lead to better compliance for many women, especially if it’s given in an accelerated manner. Additionally, while whole-breast radiation did have slightly better outcomes, the difference between the 2 was minimal, according to the study, which involved about 4200 women with breast cancer.
At the median follow-up of 10.2 years, the researchers found low recurrence rates, less than a percentage point off.
“The local recurrence rate was about 3.9% in the whole-breast radiation arm, and it was 4.6% in the partial-breast [arm],” said study investigator Julia White, MD, professor of radiation oncology at The Ohio State University Comprehensive Cancer Center.
White explained that if clinicians keep in mind the total overall dose, they may be able to give more radiation per day, thus shortening the course of treatment for eligible patients. In her practice and on the clinical trial, she used a regimen of 10 fractions, 10 treatments, given twice a day, 5 days a week. The treatments are typically broken up by a weekend.
“It’s done in 5 days. So, someone who lives far away can stay with a friend or family member, or maybe even a hotel, and get their radiation. That’s the idea of accelerated partial-breast radiation,” White said.
Disease Risk Plays a Role
Other studies comparing whole-breast versus partial-breast radiation still use 15 to 16 treatments, and typically involve patients with low-risk, stage I disease.
“There are 2 or 3 other studies, but they all focused on the low-risk, luminal A group, [with patients whose disease was] mostly node-negative,” White said. “Our question was: Is partial-breast radiation equivalent to whole-breast radiation across the spectrum of all women who get a lumpectomy, not just the low-risk women?”
And while White and her team’s study looked at women overall, she did mention that the low-risk group had lower event rates.
“So, the difference might not be so clinically meaningful, but in subtypes or risk groups where the recurrence rates are higher, then those differences between whole-breast and partial-breast are more meaningful, clinically,” she said. “The good news is that the event rates were low altogether.”
White said that she believes partial-breast radiation would be best suited for stage I, ER-positive patients who are over the age of 50 and on endocrine therapy. “But based on our trial, it won’t replace whole-breast radiation for everybody.”
While studies like these continue to enlighten practitioners on the best way to use radiation oncology, there is still more work that needs to be done.
“I think the next step for this research is to fine-tune how we deliver radiotherapy,” White said. “There’s a learning curve to every new technology that we adapt and put into practice. It’s important for us as a specialty to continue researching what are the best methods.