Patients who underwent pathology evaluation of their sentinel lymph nodes during mastectomy surgery may have been significantly more likely to receive aggressive nodal therapy than patients whose lymph node biopsies and treatment strategies were evaluated after surgery. The new findings were presented by Pride et al at the 24th American Society of Breast Surgeons (ASBrS) Annual Meeting.
Sentinel lymph node biopsies are typically performed during mastectomy procedures, but the timing of the interpretation of the results may be variable. By contrast, for lumpectomy, physicians typically interpret the results after surgery.
“This large national study is notable because it provides evidence that a significant percentage of the patients [undergoing mastectomy] with limited disease in up to two [sentinel lymph nodes] may be overtreated with axillary node dissection…or a combination of both [axillary node dissection] and postsurgical axillary radiation therapy simply because their pathology results are read and acted on while they are on the operating table,” explained senior study author Olga Kantor, MD, MS, Assistant Professor of Surgery at Harvard Medical School. Dr. Kantor is a breast surgical oncologist at Brigham and Women’s Hospital, Brigham and Women’s Faulkner Hospital, and the Dana-Farber Brigham Cancer Center.
The investigators suggested that although potentially avoiding a second surgery of the axilla, intraoperative pathology assessment may influence axillary node dissection decision-making—which often does not take place in the context of the patient’s overall treatment plan that may include radiation. This may lead some patients to receive both therapies.
The investigators noted that in the AMAROS clinical trial involving a similar patient population who had limited nodal disease and were undergoing mastectomy, researchers found that axillary node dissection and axillary radiation therapy may provide excellent and comparable axillary control.
“However, radiotherapy is often preferable because it avoids surgical morbidities, including debilitating lymphedema. Moreover, in some cases of micrometastatic nodal disease, patients may avoid both procedures with just ongoing observation of the axilla,” Dr. Kantor emphasized. “We conducted this study to assess the impact of the two practice patterns in a large mastectomy patient cohort,” she added.
Study Methods and Results
In the new study, the investigators used the National Cancer Database from 2018 to 2019 to identify 8,216 AMAROS-eligible patients with breast cancer who underwent mastectomy. The patients involved in the study had tumors up to 5 cm, presented as clinically node-negative, did not receive any presurgical treatment, and were found to have one or two positive nodes after undergoing sentinel lymph node biopsy.
The researchers reported that in 37.2% (n = 3,057) of the patients, intraoperative pathology was performed and acted upon; in 62.8% (n = 5,159) of the patients, the pathology was not performed or acted upon. Further, 33.2% (n = 2,730) of the patients received axillary management, 26.6% (n = 2,184) received axillary node dissection, 22.2% (n = 1,820) received axillary radiation therapy, and 18.0% (n = 1,482) received both axillary node dissection and axillary radiation therapy.
On a multivariate analysis adjusting for patient and tumor characteristics, intraoperative pathology assessment and real-time axillary surgical decision-making—not clinical criteria such as an increasing the number of positive lymph nodes or the size of nodal metastases—was the strongest predictor of whether a patient ultimately received both procedures.
The researchers found that 40.2 % of patients—43.4% of those with macrometastases and 17.2% with micrometastases—were treated with both axillary node dissection and axillary radiation therapy following intraoperative pathology assessment. A total of 4.9% of all patients, 7.3% of those with macrometastases, and 0.6% of those with micrometastases were similarly treated with postoperative pathology interpretation and decision-making. Notably, only a small percentage of patients returned to the operating room for axillary node dissection when the pathology was examined after mastectomy.
“The results of the study are clear—a large number of [patients] are potentially being overtreated when axillary management decisions are made intraoperatively,” Dr. Kantor underscored. “Notably, postsurgical decisions typically involve a multidisciplinary team—including radiation oncologists—which will likely result in a more integrated overall treatment plan. This study suggests that surgeons should delay [axillary node dissection] decision-making until a later time to avoid overtreating patients,” he concluded.
Disclosure: For full disclosures of the study authors, visit breastsurgeons.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.