SEATTLE – Sentinel lymph node biopsy is widely used in patients with early-stage breast cancer for staging the axilla, but it can be safely omitted in some patients, according to new research presented at the annual Society of Surgical Oncology Cancer Symposium.
In women aged 70 years and older with hormone receptor (HR)–positive invasive breast cancer, the risk of nodal involvement is 14%-15%, which adds support to the premise that sentinel lymph node surgery could be avoided in many of the women deemed to be low risk.
The Choosing Wisely campaign was initiated to reduce excess cost and expenditures in health care. The Society of Surgical Oncology recently released five Choosing Wisely guidelines that included specific tests or procedures commonly ordered but not always necessary in surgical oncology, explained study author Jessemae Welsh, MD, of the Mayo Clinic, Rochester, Minn. One of the recommendations was to avoid routine sentinel node biopsy in clinically node-negative women over age 70 years with hormone receptor–positive invasive breast cancer.
“Their rationale is that hormone therapy is the standard of care in these women and sentinel node surgery has shown no impact on local regional recurrence or breast cancer mortality,” said Dr. Welsh. “Therefore it would be safe to treat this population without any axillary node staging.”
She noted that the average 70-year-old woman may live another 14-16 years. “So the question is, how should we be applying the Choosing Wisely guidelines?”
Dr. Welsh and her colleagues evaluated the factors that might be impacting nodal positivity in this population, and in particular, they looked at T stage and tumor grade.
They used two large databases to identify all women over the age of 70 years with HR+ cN0 invasive disease in the institutional breast surgery database (IBSD, 2008-2016) from the Mayo Clinic and the National Cancer Database (NCDB, 2004-2013).
The rates of patients who were node positive (pN+) were based on those who had undergone axillary surgery.
The researchers then stratified patients by clinical T stage and tumor grade to compare risk of pN+ across strata.
Of 705 selected patients in the IBSD, 191 or 14.3% were pN+ and a similar rate was observed in the NCDB; 15.2% (19,607/129,216). Tumor grade and clinical T stage were associated with pN+.
“The overall rates were about 14% for both databases, and when we stratified this by T stage, we could see increasing node positivity with increasing T stage,” said Dr. Welsh.
In similar fashion, the researchers observed comparable increases when they stratified it by grade. “Increasing grades were associated with increasing rates, especially for grade 2 and higher,” said Dr. Welsh.
When the two factors were combined, the researchers were able to define low-risk criteria as clinical T1a-b, grade 1-2 or clinical T1c, grade 1. The low-risk group accounted for 54.3% (IBSD) and 43.2% (NCDB) of patients, and pN+ rates within this group were 7.6% (IBSD) and 7.4% (NCDB).
Patients outside of this subcohort had pN+ rates of 22.4% (IBSD) and 23.0% (NCDB), which extrapolated to a relative risk of 2.95 (95% CI: 1.97-4.42) and 3.11 (95% CI: 2.99-3.23), respectively (each P less than .001).
“Women in the high-risk group had three times the risk of node positivity as the low-risk group,” she said. “Based on our data, we can say that for grade 1 T1a-c we can omit sentinel node surgery, and also for grade 2 T1 a-b.”
But for grade 3, T2 or higher, or any grade 2 Tc tumors, clinicians should continue to consider sentinel node surgery, taking into account individual patient factors.
The investigator had no disclosures.