Younger post-menopausal women with early-stage hormone receptor–positive (HR-positive)/human epidermal growth factor receptor 2–negative (HER2-negative) breast cancer may be able to safely omit radiation therapy, provided they continue to receive endocrine therapy, according to the IDEA clinical trial presented at the San Antonio Breast Cancer Symposium held December 5–9.
The results of the study were published December 7 in the Journal of Clinical Oncology.
The clinical trial enrolled 200 participants ages 50 to 69 who had stage 1 HR-positive, HER2-negative breast cancer. The Oncotype DX score was used to determine each patient’s risk of recurrence according to the genetic profiles of their tumors. Patients with a low risk of recurrence were eligible to skip radiation therapy after breast-conserving surgery while still receiving standard-of-care endocrine therapy for at least five years.
Among the 186 study participants, 100 percent were alive five years after surgery, and 99 percent (184 participants) were breast cancer free at this time.
The lead researcher, Reshma Jagsi, MD, DPhil, who is the Lawrence W. Davis Professor and Chair of Radiation Oncology at the Emory University School of Medicine and a researcher at the Winship Cancer Institute of Emory University in Atlanta, says the study emanated from earlier research in older patients.
“The reason we did this study among this age group is that there was robust evidence from long-term follow-up of a trial in women age 70 and older that showed that the risk of breast cancer coming back was 10 percent if they got endocrine therapy alone and 2 percent if they got radiation,” Dr. Jagsi says. “We wanted to see if we could narrow this down to women ages 50 to 69, who fit certain specific criteria, and offer this option to them.”
And, in a study conducted in February among women ages 65 or older who had low-risk HR-positive breast cancer and no lymph node involvement who were treated with breast-conserving surgery and endocrine therapy, omission of radiation was associated with an “increased incidence of local recurrence but had no detrimental effect on distant recurrence” or overall survival.
The possibility of enabling patients to make decisions about their treatment options is of utmost importance, she adds.
“By offering more nuanced choices to patients, they get to regain that sense of control that their cancer diagnosis took from them in the first place,” she says.
And, while there have been significant advances in radiation treatment, being able to forego it could be a welcome option.
“Although techniques of radiation treatment have improved dramatically and it is far more efficient and tolerable now than it used to be, patients appreciate having a choice about their treatments,” she says. “Yes, we can administer treatment in five days, the vast majority tolerate it extremely well, and it’s not the many weeks of burdensome treatment it once was, but, for some, we’re learning that this may be something you can safely skip.”
And, while this study is promising, longer-term follow-up of this study and others will be essential to determine whether this option can be safely offered to women in this age group, notes Jagsi.
“For those with excellent prognoses and outcomes, we’re starting to peel back treatments and give people choices,” she says. “For example, we can talk about which side effects they’re willing to tolerate and for what benefits. Trials like this are helping to return that agency to the person who has been diagnosed.”
