Patients 65 years old or older with early endocrine-responsive breast cancer have many treatment options, including no radiation. This study aimed to evaluate treatment preference when intraoperative radiation therapy (IORT) is offered in this population.

The study reviewed patients 65 years old or older with a diagnosis of early-stage endocrine-responsive breast cancer in 2016-2019 at a single hospital in a large integrated health care system. Electronic medical records of multidisciplinary breast tumor board discussion, treatment options documented by the treatment team, and final treatment offered were reviewed. Variables including age at biopsy, language, endocrine treatment, and comorbidities were collected. Regression analysis was used to evaluate for variables associated with patients' choice regarding radiation treatment.

The institutional IORT guidelines were met by 63 patients in the described age group who had a documented offer of all radiation treatment options. The median age of the patients was 70 years (interquartile range 63-77 years). Overall, 74.6% of the patients chose IORT, and 14.3% opted for whole-breast irradiation. Only 4.8% chose to omit radiation after breast-conserving surgery, and 6.3% chose mastectomy. The patients who chose IORT were more likely to receive endocrine treatment (odds ratio 3.70; p = 0.03). Age, race, language, and comorbidities were not associated with preference for IORT (p < 0.05).

Patients 65 years old or older with early-stage endocrine-responsive breast cancer preferred to have IORT despite counsel about the lack of survival benefit. This study suggests that local cancer control with the convenient radiation delivery method is important to the described patient population.