Study details
This study, known as the ACOSOG (Alliance) Z11102 trial, was a phase 2 trial conducted in 204 patients enrolled between 2012 and 2016 who had two or three sites of biopsy-proven breast cancer (each site less rhan 5 cm in size, with cN0 or cN1 disease).
These patients were a median age of 61 years, and 83.5% were ER-positive/HER2-negative, 11.5% were HER2-positive, 5.0% were ER-negative/HER2-negative, and 77.5% were node-negative.
All patients were treated with breast conservation surgery, including lumpectomy resected to negative margins, followed by whole breast radiation with a cavity boost to all lumpectomy beds.
With a median follow-up of 66.4 months, six patients developed local recurrence, with five of the recurrences occurring in the ipsilateral breast and one in the chest wall.
For the primary endpoint, the six recurrences represented an estimated cumulative incidence of local recurrence of 3.1% (95% CI, 1.3-6.4), well below the cutoff of 8% that was determined to be the acceptable 5-year local recurrence rate based on historic recurrence rates for unifocal disease, Dr. Rosenkranz explained.
There were no cases of synchronous local and distant recurrences, six contralateral breast cancers, and three new primary nonbreast cancers. Eight patients died, including one related to breast cancer.
There were no significant associations between risk of local recurrence and factors including patient age, number of sites of preoperative biopsy-proven breast cancer, HER2 status, and pathologic T and N category.
In terms of secondary endpoints, 14 patients (7.1%) converted to mastectomy because of positive margins, while 67.6% achieved margin-negative excision in a single operation.
Regarding cosmesis, 70.6% of patients reported good or excellent cosmetic outcomes at 2 years.
In terms of adherence, the whole breast radiation therapy protocol was feasible in most patients.
Of note, among patients without a breast preoperative MRI, the 5-year rate of local recurrence was significantly higher, at 22.6% (n = 14) at 5 years, compared with 1.7% among the 180 patients who did have a preoperative MRI (P = .002). However, Dr. Rosenkranz said these differences should be interpreted with caution.
“We may look at these data and think we should consider preoperative breast MRI in patients who do have known multiple ipsilateral breast cancer, although I think this cohort was certainly much too small to draw definitive conclusions, and this was not a planned secondary endpoint of the trial,” she said during her presentation.
Most prefer breast conservation, when possible
Overall, the findings are important considering the array of known benefits of breast conservation over mastectomy, Dr. Rosenkranz concluded.
“The reason this is so important is that we know that patients who undergo breast conservation report improved quality of life, self-esteem, and body image, and therefore it’s incumbent on us as surgeons to expand the indications for breast conservation where we can,” she told the audience.
Speaking with this news organization, she added that the decision-making around breast conservation versus mastectomy can be complicated, and some women do opt for mastectomy because of a variety of factors; therefore, “tailoring therapy to the individual goals and priorities in addition to the disease characteristics is critical.”
That said, she added that “the majority of patients who are eligible for breast conservation do prefer this option.”
Dr. Rosenkranz and Dr. Cody have reported no relevant financial relationships.
A version of this article originally appeared on Medscape.com.