Sept. 21, 2023
Surgical oncologists at Mayo Clinic have found that breast-conserving therapy (BCT), including lumpectomy followed by whole breast radiation along with radiation boosts to each lumpectomy site, results in a notably low five-year local recurrence (LR) rate for women with multiple ipsilateral breast cancer (MIBC). Results of the prospective clinical trial run through the Alliance for Clinical Trials in Oncology were published in the Journal of Clinical Oncology in June 2023.
"This study opens up more treatment options for patients with breast cancer who have two or three tumors in their breast, empowering patients and their breast care teams with the data to make informed decisions," says Judy C. Boughey, M.D., a breast surgical oncologist at Mayo Clinic Comprehensive Cancer Center in Rochester, Minnesota. Dr. Boughey is also the chair of Breast and Melanoma Surgical Oncology.
BCT is the preferred treatment for unifocal breast cancer due to prospective studies showing its safety relative to mastectomy. However, mastectomy has remained the most common treatment for MIBC, as BCT's oncologic safety had not been demonstrated in a prospective study. Given recent advancements in breast cancer management, this study was conducted to assess the safety and efficacy of BCT in MIBC.
"Provided that surgery maintains adequate breast volume, breast-conserving surgery should be considered for patients with multiple ipsilateral breast cancer."
In this phase 2, single-arm, prospective trial, BCT in women with MIBC had a five-year LR rate of 3.1%, comfortably below the 8% threshold deemed clinically acceptable. The study concluded that BCT is a reasonable surgical option for people with two or three lesions in the same breast, especially if their evaluations include preoperative breast MRI.
"Provided that surgery maintains adequate breast volume, breast-conserving surgery should be considered for patients with multiple ipsilateral breast cancer," says Dr. Boughey.
The study cohort consisted of women age 40 years and older with two or three foci of biopsy-proven cN0-1 breast cancer who were interested in pursuing BCT. From the initial 270 women enrolled between 2012 and 2016, 204 were eligible and completed BCT. Of these, 193 additionally completed radiation. The median age was 61 years (range, 40 to 87 years).
Patients underwent lumpectomies with negative margins followed by whole breast radiation with a boost to all lumpectomy beds. The primary endpoint was a five-year LR rate of less than 8% for BCT.
Variables like age, number of preoperative biopsy proven sites of disease, estrogen receptor status and HER2 status did not correlate with LR risk.
Endocrine therapy's role in reducing local recurrence rates
Patients who had endocrine receptor-positive disease and opted out of endocrine therapy had higher LR rates. This underscores the importance of endocrine therapy in maintaining low LR rates.
Preoperative MRI may benefit MIBC patients undergoing BCT
An unexpected finding emerged during an unplanned secondary analysis. Among the 15 patients who did not undergo preoperative breast MRI, the five-year LR rate was 22.6%. In contrast, those who had the MRI (n = 189; P = .002) showed a 1.7% LR rate. While definitive conclusions cannot be drawn on this secondary analysis because the group that did not have a preoperative MRI is small, Dr. Boughey suggests preoperative breast MRI would be sensible for patients with two or more foci who are considering breast-conserving therapy.
Personalizing therapeutic approaches in breast cancer care
This study's findings broaden treatment options for breast cancer. For patients with MIBC, the decision regarding mastectomy or BCT is contingent on multiple factors, including tumor size, breast size and patient preference.
"Breast cancer treatment is continuously evolving, providing more options for patients," says Dr. Boughey.
This shift in perspective encapsulates the essence of modern medicine: personalized care. Advances in imaging and a diverse array of systemic therapy options support a nuanced treatment approach, often less invasive than before.
For more information
Boughey J, et al. Local recurrence after breast-conserving therapy in patients with multiple ipsilateral breast cancer: Results from ACOSOG Z11102 (Alliance). Journal of Clinical Oncology. 2023; 41:3184.
Refer a patient to Mayo Clinic.