Some younger women with early breast cancer may be able to omit adjuvant radiotherapy
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Key takeaways:
- All patients remained alive 5 years after breast-conserving surgery without radiotherapy.
- Longer follow-up will determine whether the option of avoiding initial radiotherapy can be offered to a broader group of women.
Younger postmenopausal women who underwent treatment without radiotherapy for early-stage hormone receptor-positive breast cancer experienced low 5-year recurrence rates, according to results presented at San Antonio Breast Cancer Symposium.
Longer follow-up from this trial and others will provide important information about whether the option to avoid initial radiotherapy could be offered to more women than recommended under current guidelines, researchers concluded.
“Several recent studies have added to the evidence that many older women — aged 65 and older — with hormone-sensitive, early-stage breast cancer have the option to consider omitting radiation therapy after lumpectomy surgery and endocrine therapy,” Reshma Jagsi, MD, DPhil, FASCO, FASTRO, Lawrence W. Davis professor and chair of the department of radiation oncology at Emory University School of Medicine, told Healio.
“We wanted to see if the choice to consider omitting radiation therapy might also be possible for some younger postmenopausal women. This is important to study because, although techniques of radiation treatment have improved dramatically and it is far more efficient now than it used to be, patients appreciate having a choice about what treatments to receive.”
The IDEA trial included 186 postmenopausal women (median age, 63 years; interquartile range, 58-66) with early-stage, hormone receptor-positive breast cancer who underwent breast-conserving surgery followed by endocrine therapy.
Investigators sought to determine if radiotherapy could be safely omitted for this population.
They used clinical and biologic features — as well as the Oncotype DX (Exact Sciences) recurrence score, which predicts recurrence risk based on tumor genetic profiles — to identify patients at low risk for recurrence who would be eligible to omit radiotherapy after breast-conserving surgery while still undergoing standard adjuvant endocrine therapy for at least 5 years.
Median follow-up was 5.21 years.
All patients remained alive 5 years after surgery, and 99% (95% CI, 96-100) remained breast cancer free at that time.
Two recurrences occurred by 5 years. One patient with isolated ipsilateral axillary recurrence at 21 months underwent axillary dissection, as well as breast and regional nodal irradiation. One patient with an ipsilateral breast event at 49 months underwent repeat breast-conserving surgery. Both of these patients complied with endocrine therapy.
Six additional patients developed recurrence beyond five years. These included five with ipsilateral breast events, and one with an ipsilateral breast event and regional recurrence.
No distant recurrences occurred
Researchers reported crude rates of overall recurrence of 5% among patients aged 50 to 59 years and 3.6% among those aged 60 to 69 years.
Researchers acknowledged study limitations, including the small cohort size and short follow-up time.
“Long-term follow-up of this cohort is essential given that this is a younger postmenopausal population — especially after the typical 5-year course of endocrine therapy is completed, as these patients will live many years,” Jagsi said. “Additional data from other ongoing studies will be essential to provide sufficient evidence to determine whether radiotherapy omission can safely be offered to patients like those eligible for the IDEA trial. We intend to continue to follow patients for long-term follow-up.”
Although this study focused on the possibility of identifying certain patients who may be able to avoid radiotherapy, Jagsi emphasized how advances in radiotherapy delivery have considerably reduced toxicity and short-term burden of this treatment approach. This has improved the risk-benefit ratio, especially for women with longer life expectancies.
“Some of the headlines that went with the other recent studies this year about radiotherapy omission were certainly attention-grabbing about how patients can avoid ‘harsh’ and ‘brutal’ radiation therapy,” Jagsi told Healio. “But mischaracterization of radiotherapy as an awful experience unfairly terrifies patients who need radiation therapy, and [it] is not accurate.”
She urged “responsible interpretation” of these findings.
“Work like this seeks to improve the experiences of patients diagnosed with breast cancer by trying to identify multiple treatment options to help them regain a sense of control that a cancer diagnosis can seem like it’s taking away,” Jagsi told Healio. “We hope this work contributes in that way — specifically contributing to the identification of a new option that some women like the population studied here may choose.”
References:
- Jagsi R, et al. Abstract GS02-08. Presented at: San Antonio Breast Cancer Symposium; Dec. 5-9, 2023; San Antonio.
- Younger postmenopausal patients with early-stage breast cancer may be able to safely omit adjuvant radiotherapy (press release). Published Dec. 7, 2023. Accessed Dec. 7, 2023.
Perspective
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An ECOG study conducted about 20 years ago randomly assigned women aged older than 70 years with early-stage breast cancer and good prognosis to radiation or no radiation. Although the local recurrence rate was higher in the nonradiated group, OS was the same. That was our first indication that some subgroups may not need radiation therapy.
Radiation has gotten better over the years. We have five-fraction and six-fraction regimens, IMRT and more modern equipment. Even though radiation is less toxic now, toxicity still occurs, so it would be great if we can identify opportunities to avoid it.
In this trial, 5-year OS and breast cancer-specific survival rates were both 100%, and the 5-year freedom from recurrence was 99%. You can’t get better than that. There were very few recurrences and no distant recurrences.
This will lead to a phase 3 trial (NRG-BR007) and I suspect — based on the results we saw in San Antonio — that it will show noninferiority with omission of radiation.
Dr. Jagsi was very careful in her presentation to emphasize the type of patients for whom this should be considered — age 50 to 69 years; T1, node-negative tumors; low 21-gene recurrence score; strongly ER- and PR-positive; HER2-negative; and margins greater than 2 mm. That absolutely was the right thing to do. We cannot extrapolating these results beyond the patient populations identified in this trial.
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Jagsi R, et al. Abstract GS02-08. Presented at: San Antonio Breast Cancer Symposium; Dec. 5-9, 2023; San Antonio.
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