Is Axillary Surgery for Abemaciclib Candidacy Overused?

TOPLINE:

Women with hormone receptor (HR)–positive, human epidermal growth factor receptor 2 (HER2)–negative breast cancer who have one positive sentinel node and no high-risk features can likely be spared axillary lymph node dissection to inform candidacy for adjuvant abemaciclib, but the benefit of axillary lymph node dissection in those with two positive sentinel nodes should be evaluated on a case-by-case basis.

METHODOLOGY:

• Women with high‐risk disease who qualify for abemaciclib are those with four or more positive lymph nodes or one to three positive lymph nodes plus at least one high‐risk feature; high-risk features included tumor size of at least 5 cm, a tumor grade of 3, or Ki‐ 67 of at least 20%.
• But to determine candidacy for adjuvant abemaciclib in women with HR-positive, HER2–negative breast cancer, there is a “gray zone” for performing axillary lymph node dissection in those with one or three positive sentinel nodes who do not have any high-risk features; women with just one or two positive sentinel nodes “pose an even larger dilemma,” the authors explained.
• The current study focused on assessing the proportion of patients with one or two positive sentinel nodes, four or more lymph nodes, and no high-risk features who undergo axillary lymph node dissection to determine whether this constitutes surgical overtreatment.
• In the cohort of 22,048 patients, 6948 (32%) had four or more positive lymph nodes and 7678 (35%) had one to three positive lymph nodes with at least one high-risk feature, which qualified them for abemaciclib.
• The remaining 7422 patients (34%) had one to three positive lymph nodes without any high-risk features and did not qualify for abemaciclib.

TAKEAWAY:

• In the overall cohort, 1762 patients undergoing upfront surgery who had one to three positive sentinel nodes and no high-risk features had completion axillary lymph node dissection; among these patients, only 17% had more than four positive lymph nodes and met the criteria for adjuvant abemaciclib.
• The researchers also found that 1578 patients with one to two positive sentinel nodes and no high-risk features underwent upfront completion axillary lymph node dissection. Only 13% of these patients had four or more positive lymph nodes and met the criteria for adjuvant abemaciclib, which means dissection performed only to determine abemaciclib candidacy “would have constituted surgical overtreatment in the remaining 87% of patients,” the authors said.
• When stratifying patients by the number of positive sentinel nodes, only 10% of those with one positive sentinel node and 24% of those with two had four or more positive lymph nodes after dissection and met criteria for abemaciclib.
• The number needed to treat for each sentinel node group — defined as the number of patients who required dissection to identify one patient who met the criteria for abemaciclib — was 11 for patients with one positive sentinel node, five for those with two sentinel nodes, and two for those with three nodes.

IN PRACTICE:

“Patients with one or two positive [sentinel nodes] without one or more additional high‐risk features are unlikely to have ≥ four positive [lymph nodes] and should not be subjected to the morbidity of [axillary lymph node dissection] in order to inform candidacy for abemaciclib because of its limited benefit,” the authors said. “An individualized multidisciplinary discussion should be undertaken about the risk:benefit ratio of [axillary lymph node dissection] and abemaciclib for those with two positive [sentinel nodes].”

SOURCE:

The study was led by Austin D. Williams MD, MSEd, of Fox Chase Cancer Center, Philadelphia, Pennsylvania, and published on November 29 in Cancer.

LIMITATIONS:

The study is limited by potential selection bias related to the patients with one or two positive sentinel nodes who underwent completion axillary lymph node dissection because dissection is not standard practice in patients with limited nodal disease.

DISCLOSURES:

The work was funded by the Marlyn Fein Chapter of the Fox Chase Cancer Center Board of Associates, and the US Public Health Service. Three investigators reported consultant fees from Elucent Medical.