Certain younger postmenopausal patients with breast cancer can safely omit adjuvant radiotherapy after breast-conserving surgery and endocrine therapy without facing an increased risk of recurrence, according to study results published in the Journal of Clinical Oncology.
Prior research showed that many older patients with stage I breast cancer experience a low risk of disease recurrence and ipsilateral breast events when treated with surgery and endocrine therapy alone. While this strategy is well studied in patients aged 70 years or older, it has not been widely applied to younger postmenopausal women.
Reshma Jagsi, MD, DPhil, professor and chair of the department of radiation oncology at Winship Cancer Institute and Emory University School of Medicine, and colleagues enrolled 200 postmenopausal patients between the ages of 50 years and 69 years in the IDEA study. Patients were selected if they had a score of 18 or lower using the Oncotype DX 21-gene recurrence assay, as well as other clinical features, including post-surgical margins of 2 mm or wider and pT1N0 unifocal invasive disease.
The patients gave consent to omit radiotherapy and receive a 5-year course of endocrine therapy after completing breast-conserving surgery. The rate of locoregional recurrence at 5 years served as the study’s primary endpoint.
The researchers had access to at least 56 months of follow-up data from 186 patients (median age, 63 years; interquartile range, 58-66). In total, 70% of the overall population were aged between 60 and 69 years, with the remaining 30% aged between 50 and 59 years.
Among the 186 patients included in the present analysis, Jagsi and colleagues observed 5-year overall survival and event-free survival rates of 100%. Two patients died during the follow-up period. The cause of 1 patient’s death could not be determined, while the other patient’s death was deemed unrelated to breast cancer.
The cohort had a 99% rate of freedom from any recurrence at 5 years (95% CI, 96-100). One patient developed an isolated ipsilateral axillary recurrence at 21 months, while another patient experienced an ipsilateral breast event at 49 months. No distant recurrences occurred, and 6 patients experienced a recurrence after 5 years.
Based on age category, the researchers observed crude rates of any ipsilateral breast events during the entire follow-up of 3.3% in patients aged between 50 and 59 years and 3.6% among patients aged between 60 and 69 years. The crude rates of overall recurrence by age category were 5% and 3.6%, respectively.
“These data, along with longer-term follow-up and data from ongoing trials, including larger randomized trials, inform whether the option of avoiding immediate radiotherapy after breast-conserving surgery can be offered to a broader group of women than current guidelines recommend,” Jagsi and colleagues concluded. “Such efforts strive to empower patients with choices and return to them a sense of agency that can be deeply meaningful in the context of a recent cancer diagnosis.”
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Disclosures: Authors declared financial ties to drugmakers. See full study for details.
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