Despite the use of sentinel node biopsies in a majority of older women with hormone receptor-positive breast cancer, positive lymph node status is not a reliable indicator of the need for adjunctive chemotherapy, and sentinel node biopsy may be unnecessary in older women with certain low-risk cancers, a researcher told participants of the 2022 Annual Meeting of the American Society of Breast Surgeons in Las Vegas.
Katharine Yao, MD, Vice Chair of Research at NorthShore University Health System and Clinical Professor of Surgery at the Pritzker School of Medicine, University of Chicago, presented the results of a new study in which they examined the association between nodal status and 21-gene recurrence scores using the National Cancer Database to analyze 28,338 patients 70 years of age or older.
The 21-gene recurrence score-a prognostic and predictive assay which reflects a tumor's individual biology for hormone receptor (HR)+/HER2-/node breast cancer-is considered one of the most accurate tools for chemotherapy decision-making.
Yao said that, while the 2016 Choosing Wisely guidelines advise against performing sentinel node biopsies on women 70 years of age or older, studies show physicians continue to perform them for 65-85 percent of their patients. One reason surgeons continue to perform sentinel node biopsy on this patient population is to obtain nodal status for adjuvant chemotherapy decisions, she told a press briefing.
However, the study found that, regardless of their nodal status, a similar proportion of these women had 21-gene recurrence scores qualifying them for adjuvant chemotherapy.
"Women may request sentinel node biopsies because cancer that has spread to the lymph nodes has become virtually synonymous with poor prognosis in the popular media," Yao said. "However, we are learning that there is more to tumor biology then just nodal status. Sentinel node biopsy for women older than age 70 with hormone receptor-positive breast cancer is not really helpful for making adjuvant chemotherapy decisions. While eliminating sentinel node biopsy may seem counter-intuitive to some patients, it is not likely to have a major impact on their outcomes."
She and her colleagues reviewed outcomes among women who were treated for HR+, HER2-, AJCC clinical stage T1-T2 breast cancers between 2010 and 2018. They examined the correlation of nodal status with 21-gene recurrence results and also identified other clinical and demographic factors associated with high 21-gene recurrence scores and the need for chemotherapy.
Among the patients, 5,640 (19.9%) were node-positive and 22,698 (80.1%) were node-negative. The investigators found that the proportion of patients with a 21-gene recurrence score greater than or equal to 26 was 3,330 (13.1%) for node-negative patients and 740 (14.7%) for node-positive patients. A score equal to or greater than 26 typically indicates that chemotherapy will be beneficial.
"A similar proportion of women 70 years old with AJCC Stage I HR+, HER2- breast cancer have Oncotype DX scores >=26 regardless of their nodal status," Yao said. "These findings suggest that sentinel node biopsy may not be helpful for adjuvant chemotherapy decisions in this patient population, but certain tumor factors may be more helpful."
For both node-negative and node-positive patients, a Grade 3 tumor was associated most strongly with a high 21-gene recurrence score, followed by negative progesterone receptor status. Women with tumors greater than 2 cm and patients covered by Medicaid also were more likely to have a cancer recurrence score greater than or equal to 26, the researchers found. Hispanic patients were less likely to have a 21-gene recurrence score qualifying them for chemotherapy compared to Black and Asian women.
Yao noted that sentinel node biopsy carries some associated morbidity and is an additional operating room procedure. "However, it may not provide the necessary information for decision-making about adjuvant chemotherapy. For this patient population, consideration of other tumor factors, including possibly an Oncotype score, may be more useful than nodal status."
Kurt Samson is a contributing writer.