SENOPAUSE: Evaluation of an ASCO-Derived Clinical Proxy for Axillary Risk Stratification in a Retrospective Cohort.

BACKGROUND

Sentinel lymph node biopsy (SLNB) omission is increasingly considered in carefully selected postmenopausal patients with low-risk, early-stage breast cancer. However, the prevalence of occult nodal disease and wether nodal information alters adjuvant management remain key concerns in real-world implementation.

METHODS

We conducted a retrospective, two-center observational study using an institutional REDCap database. Consecutive patients treated surgically between 2023 and 2024 were screened and a strict proxy of ASCO eligibility criteria for SLNB omission was applied (postmenopausal; HR-positive/HER2-negative; invasive ductal carcinoma; T0 to T1; grade 1 to 2; no neoadjuvant therapy). The primary outcome was the prevalence of pN1 disease within the ASCO-eligible cohort. Secondary outcomes included adjuvant chemotherapy use, whole-breast radiotherapy (WBRT), and availability of genomic testing.

RESULTS

Among 662 screened patients, 211 met all ASCO proxy eligibility criteria. Occult nodal involvement was observed in 20/211 patients (9.5%, pN1). Adjuvant chemotherapy was administered in 10/211 patients (4.7%), while WBRT was delivered in 203/211 (95.7%). Genomic testing was available in 17/211 patients (8.1%) and was predominantly low-risk among those tested (13/17, 76%). Within the pN1 subgroup (n = 20), chemotherapy was administered in 4/20 patients (20%), and genomic testing was available in 8/20 (40%).

CONCLUSION

In a real-world cohort meeting strict ASCO proxy criteria, approximately 1 in ten patients had occult pN1 disease, yet chemotherapy use remained uncommon and WBRT was near-universal. These findings suggest nodal status may have limited impact on downstream adjuvant treatment escalation in highly selected low-risk luminal breast cancers.