Association between tumor biology and occult lymph node metastases before and after primary neoadjuvant therapy (NAT) for patients with early breast cancer

Background:

It is still unclear if the approach of de-escalation regarding axillary intervention is feasible in all breast cancer subtypes based on their risk of axillary involvement. We analyzed the association of tumor biology and occult axillary involvement with data from arms A/B of the SENTINA trial.

Methods:

Patients with a clinically negative axilla before NAT were included. All patients received SLNB before NAT, in cases of negative SLNB without further axillary surgery (Arm A) and in cases of positive SLNB (Arm B) with SLNB and axillary dissection after NAT. We evaluated the association between tumor biology and axillary involvement before and after NAT.

Results:

Of the 1022 patients in arms A/B of the SENTINA trial 926 were evaluable. 27.9% had triple negative (TN), 16.3% hormone receptor (HR) and HER2 positive (triple positive = TP), 47.6% HR positive and HER2 negative (luminal) and 8.2% HR negative and HER2 positive (HER2) tumors. Rates of involved SLN before NAT were 39.7% (luminal), 28.9% (HER2), 19% (TN) and 47% (TP). Subgroup comparisons showed a significant difference between luminal and TN, the differences between luminal and TP and HER2 were not statistically significant. The analysis after NAT showed trends for lower rates of involved lymph nodes for the high-risk groups without statistical significance.

Conclusions:

Among patients enrolled in the SENTINA trial, patients with triple negative disease have the lowest risk for occult lymph node metastases at initial presentation. Our results do not justify more intense axillary intervention among patients with triple negative breast cancer.