Ultrasound-Based Nomogram Identifies Breast Cancer Patients Unlikely to Harbor Axillary Metastasis: Towards Selective Omission of Sentinel Lymph Node Biopsy.

BACKGROUND: As tumor biology takes precedence over anatomic staging to determine breast cancer (BC) prognosis, there is growing interest in limiting axillary surgery. There is a need for tools to identify patients at the lowest risk of harboring axillary lymph node (ALN) disease, to determine when omission of sentinel lymph node biopsy (SLNB) may be appropriate. We examined whether a nomogram using preoperative axillary ultrasound (axUS) findings, clinical tumor size, receptor status, and grade to calculate the probability of nodal metastasis (PNM) has value in surgical decision making. METHODS: This was a retrospective analysis of female patients (February 2011-October 2014) with invasive BC who underwent preoperative axUS and axillary surgery. Cases with locally advanced BC, neoadjuvant treatment, or bilateral BC were excluded. PNM was calculated for each case. Using various PNM thresholds, the proportion of cases with ALN metastasis on pathology was examined to determine an optimal PNM cut-point to predict ALN negativity. RESULTS: Of 357 included patients, 72% were node-negative on surgical staging, and 69 (19.6%) had a PNM < 9.3%. Of these 69 patients, 6 had ALN metastasis on surgical pathology, yielding a false negative rate (FNR) of 8.7% for predicting negative ALN when a PNM threshold of < 9.3% was used. CONCLUSION: A nomogram incorporating axUS findings and tumor characteristics identified a sizeable subgroup (19.6%) in whom ALN was predicted to be negative, with an 8.7% FNR. Surgeons can use this nomogram to quantify the probability of ALN metastasis and select patients who may benefit from omitting SLNB.

Positive Ultrasound-guided Lymph Node Needle Biopsy in Breast Cancer may not Mandate Axillary Lymph Node Dissection.

BACKGROUND: The ACOSOG Z0011 (Z11) trial demonstrated that in patients with nonpalpable axillary lymph nodes (LN) and one to two positive sentinel LN (SLN), axillary LN dissection (ALND) is unnecessary.JAMA 305:569-575, [2011], Ann Surg 264:413-42, [2016] The Z11 trial did not require preoperative axillary ultrasound (axUS). In many centers, preoperative axUS is part of the standard workup of a newly diagnosed breast cancer patient, but in light of the Z11 results, its role is now questioned. METHODS: We retrospectively analyzed newly diagnosed breast cancer patients at two institutions. Inclusion criteria were patients with (1) no palpable lymphadenopathy, (2) abnormal axUS, (3) axillary LN metastasis confirmed preoperatively by axUS-lymph node needle biopsy, (4) no neoadjuvant therapy, and (5) ALND. LN disease burden was dichotomized as N1 versus N2-3. We examined relationships between clinicopathologic factors, including axUS characteristics, and LN disease burden. RESULTS: Of 129 included cases, 67 had N1 disease (51.9%) and 62 had N2-3 disease (48.1%). Factors significantly associated with N1 disease were tumor size ≤2 cm (p = 0.012), nonlobular histology (p = 0.013), and one suspicious LN on axUS (p = 0.008). For patients with both tumor size on imaging ≤2 cm and one abnormal LN on axUS, only 27% had N2-3 disease (p = 0.007). CONCLUSIONS: More than half of patients without palpable adenopathy but with preoperative US-guided biopsy proven axillary LN metastases had N1 disease. For patients with both tumor size ≤2 cm and only 1 abnormal LN on axUS, 73% had N1 disease. This suggests that such patients, if they are otherwise analogous to Z11 patients, may undergo attempt at SLNB.