Dr. Boughey on Key Results From the ACOSOG Z11102 Trial in Multiple Ipsilateral Breast Cancer

Judy C. Boughey, MD, breast surgical oncologist, division chair, Breast and Melanoma Surgical Oncology, chair, Breast Cancer Disease Group, Mayo Clinic Comprehensive Cancer Center, discusses the significance of results from the phase 2 ACOSOG Z11102 (Alliance) trial (NCT01556243) evaluating breast conserving therapy (BCT) in multiple ipsilateral breast cancer (MIBC). 

The single-arm, prospective trial evaluated the effect of BCT when combined with whole breast radiation therapy on the local recurrence rate in patients over 40 years of age with MIBC. The study enrolled 270 patients, 204 of which were deemed evaluable, with the primary end point of a 5-year local recurrence rate for BCT, which was defined as less than 8%. 

Results from the trial were presented at the 2022 San Antonio Breast Cancer Symposium, whichdemonstrated that the estimated 5-year local recurrence rate was 3.1%, which was deemed clinically acceptable, Boughey states. Patients with endocrine receptor (ER)–positive breast cancer who did not pursue endocrine therapy had a higher rate of local recurrence compared with patients who did, Boughey says. This indicates that adherence to endocrine therapy is associated with low rates of local recurrence across most breast cancer populations, she explains. Other factors such as patient age, number of preoperative biopsy sites, and HER2 status were not found to be associated with risk of local recurrence.

Moreover, the study included 15 patients who did not undergo a preoperative breast magnetic resonance imaging (MRI) scan, Boughey continues. An unplanned secondary analysis of this population revealed that these patients had a significantly higher rate of local recurrence than those who underwent preoperative breast MRIs.

Definitive conclusions cannot be drawn from these data due to the limited patient population, Boughey cautions. However, for patients who have 2 or more foci of disease in the breast, it is reasonable to suggest a breast MRI in order to evaluate the risk of disease, she says. The MRI can then evaluate the extent of a patient’s disease before they commit to the operation, Boughey concludes.