In women aged 70 and older with hormone receptor–positive, HER2-negative, low-risk breast cancers, sentinel lymph node biopsy may not be a reliable indicator of the need for adjuvant chemotherapy, researchers reported at the 2022 American Society of Breast Surgeons Annual Meeting.1
Katharine Yao, MD
“We found that the proportion of patients aged 70 and older with an Oncotype DX 21-gene recurrence score [RS] that qualifies them for adjuvant chemotherapy is fairly similar between node-negative and node-positive patients,” said the study’s senior author, Katharine Yao, MD, Clinical Professor of Surgery at the Pritzker School of Medicine of the University of Chicago and Vice Chair of Research and Development, NorthShore University Health System. Dr. Yao described her findings at a press briefing in advance of the meeting. The first study author was Kyra Nicholson, MD, also of NorthShore.
“Although eliminating sentinel node biopsy may seem counterintuitive to some patients, it is not likely to have a major impact on their outcomes,” Dr. Yao commented.
Several years ago, the Choosing Wisely initiative adopted the recommendation that sentinel lymph node biopsy (SLNB) should not be routinely used in women aged 70 and older who had clinically node-negative, early-stage, hormone receptor–positive, HER2-negative invasive breast cancer. The guideline provided, however, for axillary nodal staging if the results could impact decisions regarding adjuvant therapy.
“We suppose that many surgeons continue to perform sentinel node biopsy for these patients when making treatment decisions, but it probably shouldn’t be used for this,” said Dr. Yao. Based on the study, Oncotype DX and even clinical factors could be more informative, she suggested.
About the Study
Dr. Yao and colleagues conducted a study to determine the real value of SLNB in identifying patients who might benefit from adjuvant chemotherapy. First, the study examined the distribution of the RS in women aged 70 years and older who had hormone receptor–positive, HER2-negative breast cancer; second, it aimed to identify clinical factors associated with a high RS.
As background, Dr. Yao reviewed the findings of TAILORx, which enrolled patients with node-negative disease,2 and RxPONDER, which targeted women with node-positive disease.3 Both studies showed that for postmenopausal women with an RS of at least 26, adjuvant chemotherapy added to hormonal therapy conveyed a survival benefit.
“We wanted to see whether the Oncotype DX RS would be a better differentiator of who would benefit from adjuvant chemotherapy than a sentinel node biopsy,” she said.
Using the National Cancer Database, Dr. Yao and her team analyzed 28,338 patients aged 70 and older treated for hormone receptor–positive, HER2-negative T1/T2 breast cancers including patients with one to three positive nodes between 2010 and 2018. Approximately 20% of the patients had node-positive disease, and 80% had node-negative disease on pathology examination. The researchers examined the correlation of nodal status with the 21-gene RS and identified other clinical and demographic factors associated with a high RS and the need for chemotherapy.
Consistent with Dr. Yao’s own observations, the database showed a sharp trend in SLNB over time in this patient population, rising from 81.2% in 2012 (2 years after study initiation) to 88.5% in 2018. “The vast majority of patients in our data set underwent sentinel node biopsy,” she noted.
An RS of at least 26 typically indicates that chemotherapy will be beneficial, according to TAILORx and RxPONDER. Overall, the proportion of patients with a 21-gene RS of at least 26 was 13.1% among node-negative patients and 14.7% among node-positive patients, suggesting there is no need for the SLNB to evaluate nodal status in making treatment decisions. Although the difference was statistically significant (P = .003), the absolute difference between these groups is small, she noted.
In the multivariate analysis, a high RS was most strongly correlated with several tumor factors. For node-positive and node-negative patients, respectively, the factors and their odds ratios (ORs) were:
“It should be noted that the number of positive nodes was not associated with a high recurrence score for those patients who had node-positive disease…. Although sentinel node biopsy may not be helpful for adjuvant chemotherapy decisions in this patient population, certain tumor factors may be helpful,” she added.
The study findings could be limited by selection bias, she acknowledged, in that Oncotype DX was ordered at the clinician’s discretion, and the reason for ordering the assay was not available.
According to Sarah Blair, MD, FACS, Professor of Surgery at the University of California San Diego and Vice Chair of Academic Affairs in the Department of Surgery, the findings are further evidence that tumor genomics and tumor biology are the most important determinants of systemic
Sarah Blair, MD, FACS
therapy in patients with hormone receptor–positive disease and support other studies showing omission of SLNB in well-selected patients is oncologically safe. “Surgeons should have more confidence in ‘Choosing Wisely’ in this low-risk population,” Dr. Blair suggested.
Dr. Yao added: “I suspect the reason why so many surgeons still do sentinel node biopsy in this patient population is for radiation decisions—we did see that node–positive patients received breast radiation more frequently then node–negative patients (73.6% vs 64.2%), respectively.
DISCLOSURE: Dr. Yao and Dr. Blair reported no conflicts of interest.
1. Nicholson K, Chichura A, Kuchta K, et al: Oncotype DX recurrence scores and nodal status in patients over 70 years old: Continue to Choose Wisely. 2022 American Society of Breast Surgeons Annual Meeting. Abstract 1148608. Presented April 8, 2022.
2. Sparano JA, Gray RJ, Makower DF, et al: Adjuvant chemotherapy guided by a 21-gene expression assay in breast cancer. N Engl J Med 379:111-121, 2018.
3. Kalinsky K, Barlow WE, Gralow JR, et al: 21-gene assay to inform chemotherapy benefit in node-positive breast cancer. N Engl J Med 385:2336-2347, 2021.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®.