BOSTON — Women with breast cancer who have several tumors in one breast do not necessarily need to have a mastectomy, as new data show a low risk of recurrence at 5 years when they are treated with breast-conserving therapy and radiation.
“[The study] proves the oncologic safety of breast conservation in women with two or three sites of disease, making this a very reasonable option for (previously reluctant) surgeons to present to patients,” first author Kari Rosenkranz, MD, an associate professor at Dartmouth Health, in Norwich, Vermont, told Medscape Medical News.
The findings were presented here at the International Conference on Surgical Cancer Care (SSO 2023), and were published online March 28 in the Journal of Clinical Oncology (JCO).
Commenting on the study, Hiram S. Cody, III, MD, an attending surgeon and professor of surgery at Weill Cornell Medical College, Memorial Sloan Kettering Cancer Center in New York City, said the findings provide valuable new evidence on the issue.
“This is an important study confirming that breast conservation is feasible and safe for women with multiple ipsilateral breast cancers, with excellent results comparable to those for women with unifocal (single site) disease,” he told Medscape Medical News.
Although there have been as many as seven previous randomized trials that have shown identical outcomes in survival and local control of disease with breast-conserving therapy versus mastectomy, all those studies excluded patients with more than one site of disease.
At present, many surgeons and guidelines continue to recommend mastectomy for women with multiple-site tumors, based on older data that showed higher recurrence rates.
That is why the new study is so important, Cody explained. “Here, we see in a prospective trial that breast-conserving therapy is feasible for those with more than one site of disease as well, with high survival and very low rates of local recurrence,” he emphasized.
Cody noted that “the ideal candidate would be a woman with relatively small tumor size and a breast large enough that the multiple excisions could be performed with a good cosmetic result.”
“We have followed this approach for some time and hope that with the publication of these results more surgeons will recommend this approach for suitable patients,” he said.
The new results were also highlighted in a press release from Mayo Clinic highlighting the JCO publication. Lead author of the article, surgical oncologist Judy Boughey, MD, from the Mayo Clinic in Rochester, Minnesota, commented: “I am excited about these findings because it will empower patients and the multidisciplinary care teams caring for patients to be thinking about this option for women who may want to preserve their breast.”
This study showed the rate of cancer local recurrence was 3.1%, she noted. This is an excellent outcome and is similar to the local recurrence rate for patients with a single tumor in a breast who had breast-conserving therapy, Boughey said.
Historically, women with multiple tumors in one breast have been advised to have a mastectomy. Now, patients can be offered a less invasive option with faster recovery, resulting in better patient satisfaction and cosmetic outcomes, she added.
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 < 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, 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 due to 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 pre-operative 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, 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, 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 Medscape Medical News, she added that the decision-making around breast conservation versus mastectomy can be complicated, and some women do opt for mastectomy due to 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.”
Rosenkranz and Cody have reported no relevant financial relationships.
International Conference on Surgical Cancer Care (SSO 2023). Abstract #1. Presented March 24, 2023. Abstract
J Clin Oncol. Published online March 28, 2023.
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