Is sentinel lymph node frozen section analysis necessary in hormone receptor-positive, HER2-negative, clinically node-negative breast cancer patients undergoing upfront mastectomy?

Background: Axillary surgical management in breast cancer has recently shifted toward less invasive approaches. Although sentinel lymph node biopsy (SLNB) remains the standard method for axillary staging in clinically node-negative patients, the necessity of performing intraoperative frozen section (IFS) in those undergoing up-front mastectomy continues to be a matter of debate. Method: In this retrospective study, we evaluated 47 women aged 18 years or older who were diagnosed with hormone receptor-positive, HER2-negative cT1-3 breast cancer patients and underwent upfront mastectomy combined with SLNB between October 2022 - January 2026. Our analyses excluded patients who received neoadjuvant therapy, underwent breast-conserving surgery, or demonstrated clinical or radiological evidence of nodal involvement. SLNB was performed using a dual-agent technique. In line with institutional routine practice, SLNB were assessed on paraffin-embedded permanent sections rather than IFS analysis. We analyzed treatment processes together with clinical and pathological variables. Results: Among 47 patients, 39 (83%) were node-negative, while 8 (17%) were node-positive. There were no significant differences between the groups by age, tumor size, histopathologic subtype. Lymphovascular invasion and extracapsular extension were significantly more prevalent in SLNB-positive patients (p = 0.021). None of the node-positive patients underwent axillary dissection; instead, a multidisciplinary tumor board decision was to maintain treatment with axillary radiotherapy. The absence of IFS analysis neither altered therapeutic planning nor necessitated any additional surgical intervention. There were no regional recurrences after a median follow-up of 27 months. Conclusion: In this retrospective cohort of clinically node-negative, hormone receptor-positive, HER2-negative cT1-3 breast cancer patients undergoing upfront mastectomy, omission of intraoperative frozen section (IFS) analysis was not associated with early regional recurrence during the observed follow-up. Routine IFS would likely have altered immediate surgical management in only a small minority of patients in this selected population, suggesting limited clinical utility in similar low-risk cohorts.