Background.

The use of neoadjuvant chemotherapy (NAC) in less aggressive breast cancer (BC) is controversial.

Objective.

To investigate the effect of neoadjuvant chemotherapy in HER2 negative luminal B breast cancer.

Patients and methods.

Patients between January 2016 and December 2021 were retrospectively evaluated.

Results.

A total of 128 patients were included in the study. Patients with pathological complete response (pCR) were younger and had higher ki67 levels. Cutoff levels for ki67 based on pCR and ypT status were ≤ 40% and ≤ 35%, respectively. According to pre-NAC magnetic resonance imaging findings, only mastectomy was viable in 90 patients, but after NAC breast-conserving surgery (BCS) was possible in 29 (32%). Moreover, 68.5% became eligible for sentinel lymph node biopsy (SLNB) after NAC. Since SLNB was positive in 45 (54.2%), axillary lymph node dissection (ALND) was performed and the remainder, 38 (31.4%), avoided ALND.

Conclusion.

In patients with Luminal B, HER2(-) BC a low pCR rate should not discourage the use of NAC. The ki67 level is a guide for individualizing treatment. Especially in young patients with high ki67 levels, NAC increases the chance of breast-conserving surgery and may spare patients from ALND.

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