Impact of Omission of Sentinel Lymph Node Surgery on Radiation Treatment in Patients Age 50 and Older with Breast Cancer Treated with Lumpectomy: A Single-Institution Retrospective Review.

BACKGROUND

Recent trials demonstrated the safety of sentinel lymph node (SLN) surgery omission in low-risk patients with breast cancer. However, these trials generally included whole breast irradiation (WBI), creating the potential for radiation treatment (RT) escalation with SLN surgery omission. We evaluate the impact of SLN surgery omission on RT.

METHODS

With institutional review board approval, we conducted a retrospective review of women age ≥50 years diagnosed with cT1/cT2 estrogen receptor-positive/human epidermal growth factor receptor 2-negative breast cancer treated with breast-conserving surgery between January 1, 2020, and August 1, 2025, at a single institution. Trends were assessed with Cochran-Armitage trend tests.

RESULTS

We identified 1016 breast cancers among 999 women. SLN surgery omission significantly increased from 25.5% in 2020 to 50.9% in 2025, p<0.001. Those selected for omission of SLN surgery were older (76 vs. 64 years, p<0.001), less commonly cT2 (6.5% vs. 19.1%, p<0.001), had lower-grade breast cancer (51.5% vs. 40.1%, p<0.001), and were less likely to undergo RT (72.5% vs. 92.5%, p<0.001). Overall, in patients with omission of SLN surgery, the use of WBI was lower (21.5% vs. 50.9%, p<0.001), partial breast irradiation was higher (51.0% vs. 41.6%, p=0.004), and RT omission was higher (27.5% vs. 7.5%, p<0.001).

CONCLUSIONS

With increased adoption of SLN surgery omission from 2020 to 2025, rates of RT utilization and use of WBI did not increase. In low-risk patients selected for omission of SLN surgery, RT omission and partial breast irradiation were more common. With a multidisciplinary team approach, we are successfully de-escalating axillary surgery without escalating RT for select low-risk patients.