De-Escalated Treatment for Early Breast Cancer Continues to Gain Momentum

The number of women skipping sentinel lymph node biopsy (SLNB) for early breast cancer doubled over a 5-year period to become the predominant strategy for low-risk disease, a prospective study showed.

The proportion of patients who omitted SLNB increased from 25.5% in 2020 to 50.9% in 2025. Over the 5-year period, 69% of women ages 70 or older omitted SLNB, as did a third of patients ages 50-69. Almost 80% of women who omitted SLNB had partial breast irradiation (PBI) or no radiation therapy (RT).

More than 90% of women who underwent SLNB had no evidence of lymph node involvement, and a majority of those patients had PBI or no RT. Only three of 62 patients with positive SLNB results underwent axillary lymph node dissection (ALND), continuing a recent trend toward less aggressive management for low-risk breast cancer, said Matthew Hager, MD, of the Mayo Clinic in Rochester, Minnesota, at the American Society of Breast Surgeons meeting in Seattle.

“We saw a significant increase in patients selected for sentinel lymph node surgery omission from 2020 to 2025, initially in the 70-and-older age group and more recently in the 50-to-69 age group,” said Hager. “Importantly, rates of radiation therapy and use of whole-breast irradiation did not increase. In fact, patients who were selected for omission of sentinel lymph node surgery had lower-risk disease and were more likely to have partial breast or omission of radiation compared to those who underwent sentinel lymph node surgery.”

“With a multidisciplinary team approach, we are successfully de-escalating axillary surgery in appropriately selected patients without escalating radiation,” he added.

The findings add to a growing body of evidence that treatment de-escalation is feasible and safe for favorable-risk early breast cancer, said Youssef Zeidan, MD, PhD, of the Lynn Cancer Institute and Baptist Health South Florida in Boca Raton.

“Endocrine therapy alone or in combination with radiation therapy represents a clinically viable approach,” Zeidan, an expert for the American Society for Radiation Oncology, told MedPage Today. “However, the optimal strategy requires careful multidisciplinary deliberation that incorporates patient preferences and individual risk profiles.”

In two recent studies of axillary lymph node surgery omission — SOUND and INSEMA — most patients received whole-breast irradiation (WBI), he noted. Omission of RT warrants particular caution in younger patients given their increased risk of local recurrence. Ongoing analysis of two recently completed clinical trials — EUROPA and DEBRA — is expected to help clarify optimal management strategies for patients with favorable-risk disease.

A decade ago the Society of Surgical Oncology Choosing Wisely guidelines recommended against routine SLNB for patients older than 70 with low-risk early breast cancer. The SOUND and INSEMA trials extended the evidence supporting omission of SLNB to women older than 50, Hager noted. Additionally, several studies have demonstrated the safety of de-escalated RT for low-risk early breast cancer.

“Many of these trials omitting sentinel lymph node surgery generally required whole-breast irradiation, raising concern that omission of sentinel lymph node surgery could lead to escalation of radiation,” he said.

With input from a multidisciplinary team, Mayo Clinic implemented a policy of SLNB omission in low-risk patients, including agreement not to escalate RT. Hager reviewed findings from an analysis of the policy and the impact on RT for appropriately selected low-risk patients.

The analysis included 1,016 patients treated for low-risk breast cancer at Mayo Clinic from 2020 through 2025. Eligible patients 50 or older had tumors less than 5 cm and clinically node-negative, estrogen receptor-positive/HER2-negative breast cancer that was treated with breast-conserving surgery. Data analysis included type of axillary surgery (SLNB, ALND, or none) and type of RT (WBI, PBI, or none).

The data showed that 679 patients had SLNB and 337 did not. Patients who did not have SLNB were older (76 vs 64), less likely to have clinical T2 disease (6.5% vs 19.1%), more likely to have grade I disease (51.5% vs 40.1%), and a lower median proliferation score (8.0% vs 10.0%). Pathology confirmed T2 disease in more patients who had SLNB (18.6% vs 9.5%) and showed that more patients with SLNB had lymph node involvement (pN1, 9.1% vs 0).

In 2020, a majority of patients 70 or older had omission of SLNB (52.9%) as compared with only 1.3% of younger patients. By 2022, the omission rate jumped to 79.4% for patients 70 or older and hovered around 80% for the rest of the study period. In contrast, the omission rate in younger patients remained at about 1% until 2023 when it hit 3.2%, before increasing to 14.6% of cases in 2024 and 32.8% in 2025.

The increase in SLNB omission was not accompanied by more extensive RT, as 51% of patients had PBI and 27.5% had no RT. Among patients who underwent SLNB and had no evidence of lymph node involvement (pN0, n=617), 45.6% had PBI and 8.0% had no RT.

In the older group, 291 of 421 evaluable patients (69.1%) did not undergo SLNB, almost half of whom had PBI (48.6%) and an additional 30% had no RT. In the 130 patients who had SLNB, 56.3% received WBI. In the younger group (n=595), only 7.7% skipped SLNB, but 11% also omitted RT and 66.7% had PBI. Even in the younger patients who underwent SLNB, a majority received either PBI (44.5%) or no RT (5.8%).

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