The roles of 18F-FDG-PET/CT and US-guided FNAC in assessment of axillary nodal metastases in breast cancer patients

Axillary Reverse Mapping in Clinically Node-Positive Breast Cancer Patients

BACKGROUND

Axillary reverse mapping (ARM) nodes are involved in a significant proportion of clinically node-positive (cN+) breast cancer patients. However, neoadjuvant chemotherapy (NAC) is effective at decreasing the incidence of nodal metastases in cN+ patients.

PATIENTS AND METHODS

One hundred forty-five cN+ patients with confirmed nodal involvement on ultrasound-guided fine needle aspiration cytology were enrolled in this study: one group underwent axillary lymph node dissection (ALND) without NAC (upfront surgery group), and the other group underwent ALND following NAC (NAC group). The patients underwent 18F-FDG-positron emission tomography/computed tomography (18F-FDG-PET/CT) before surgery, as well as an ARM procedure during ALND.

RESULTS

the rates of involvement of ARM nodes in the NAC group were significantly lower than those of the upfront surgery group (36.6% vs. 62.2%, p < 0.01). Notably, involvement was significantly decreased after NAC in non-luminal-type tumors as compared to the luminal-type (18.4% vs. 48.5%: p < 0.01). Moreover, there was a significant difference in ARM node involvement after NAC between patients with or without axillary uptake of 18F-FDG (61.5% vs. 32.5%: p < 0.01).

CONCLUSIONS

NAC significantly decreased the risk of ARM node metastases in cN+ patients, but 18F-FDG-PET/CT was not suitable to detect residual metastatic disease of the axilla after NAC.

The involvement of axillary reverse mapping nodes in patients with node-positive breast cancer

INTRODUCTION

Axillary reverse mapping (ARM) procedure is useful in reducing lymphedema. However, concerns regarding oncologic safety have limited the adoption of the ARM procedure. This study aimed to evaluate the involvement of ARM nodes in node-positive breast cancer patients.

MATERIALS AND METHODS

Two hundred twenty-three node-positive patients were enrolled in this study: 90 were clinically node-negative, but had one or more positive sentinel lymph nodes (SLNs) (SLN-positive group); 68 were clinicopathologically node-positive (CpN-positive group); and 65 had confirmed nodal involvement and received neoadjuvant chemotherapy (NAC) (NAC group). All patients underwent axillary lymph node dissection with fluorescent ARM.

RESULTS

ARM nodes were involved in 33 (36.7%) patients of the SLN-group. Residual ARM nodes after SLN biopsy were involved in 11 patients (12.2%), including 5 patients (19.2%) with crossover type nodes and 6 patients (9.4%) with non-crossover type nodes. However, the difference in involvement rates between the two types was not high enough to be significant. Of these 11 patients, moreover, four patients had three or more than 3 involved SLNs. On the other hand, the involvement rate of ARM nodes in the NAC group was significantly lower than that of the CpN-positive group (35.4% vs. 64.7%: p < 0.01). Despite lower involvement, the risk of metastases in the ARM nodes was still too high to spare ARM nodes in both the NAC group and CpN-positive group.

CONCLUSIONS

Suspicious or involved ARM nodes should be removed even when detected in ARM procedure, particularly in NAC-group and CpN-positive-group patients.

ACR Appropriateness Criteria® Imaging of the Axilla

This publication reviews the current evidence supporting the imaging approach of the axilla in various scenarios with broad differential diagnosis ranging from inflammatory to malignant etiologies. Controversies on the management of axillary adenopathy results in disagreement on the appropriate axillary imaging tests. Ultrasound is often the appropriate initial imaging test in several clinical scenarios. Clinical information (such as age, physical examinations, risk factors) and concurrent complete breast evaluation with mammogram, tomosynthesis, or MRI impact the type of initial imaging test for the axilla. Several impactful clinical trials demonstrated that selected patient's population can received sentinel lymph node biopsy instead of axillary lymph node dissection with similar overall survival, and axillary lymph node dissection is a safe alternative as the nodal staging procedure for clinically node negative patients or even for some node positive patients with limited nodal tumor burden. This approach is not universally accepted, which adversely affect the type of imaging tests considered appropriate for axilla. This document is focused on the initial imaging of the axilla in various scenarios, with the understanding that concurrent or subsequent additional tests may also be performed for the breast. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diagnostic Performance of FDG-PET/CT Scan as Compared to US-Guided FNA in Prediction of Axillary Lymph Node Involvement in Breast Cancer Patients

Purpose

The aim of this study was to evaluate the diagnostic ability of 2-deoxy-2-[fluorine-18]fluoro-d-glucose (¹⁸F-FDG) PET/non-contrast CT compared with those of ultrasound (US)-guided fine needle aspiration (FNA) for axillary lymph node (ALN) staging in breast cancer patients.

Patients and Methods

Preoperative ¹⁸F-FDG PET/non-contrast CT was performed in 268 women with breast cancer, as well as ALN dissection or sentinel lymph node (SLN) biopsy. One hundred sixty-four patients underwent US-guided FNA in combination with ¹⁸F-FDG PET/CT. The diagnostic performance of each modality was evaluated using histopathologic assessments as the reference standard. The receiver operating characteristic (ROC) curves were compared to evaluate the diagnostic ability of several imaging modalities.

Results

Axillary ¹⁸F-FDG uptake was positive in 180 patients, and 125 patients had axillary metastases according to the final pathology obtained by ALN dissection and/or SLN dissection. Of the patients with positive ¹⁸F-FDG uptake in the axilla, 21% had false-positive results, whereas 79% were truly positive. Eighty-eight patients had negative ¹⁸F-FDG uptake in the axilla, among which 25% were false-negative. ¹⁸F-FDG-PET/CT had a sensitivity of 86.59% and a specificity of 63.46% in the assessment of ALN metastasis; on the other hand, US-guided FNA had a sensitivity of 91.67% and a specificity of 87.50%. The mean primary cancer size (p = 0.04) and tumor grade (p = 0.04) in combination were the only factors associated with the accuracy of ¹⁸F-FDG PET/CT for detecting metastatic ALNs.

Conclusion

The diagnostic performance of ¹⁸F-FDG PET/CT for the detection of axillary node metastasis in breast cancer patients was not significantly different from that of US-guided FNA. Combining ¹⁸F-FDG PET/CT with US-guided FNA or SLN biopsy could improve the diagnostic performance compared to ¹⁸F-FDG PET/CT alone.

Breast cancer preoperative 18FDG-PET, overall survival prognostic separation compared with the lymph node ratio

PURPOSE

To evaluate the overall survival prognostic value of preoperative 18F-fluorodeoxyglucose positron emission tomography (PET) in breast cancer, as compared with the lymph node ratio (LNR).

METHODS

Data were abstracted at a median follow-up 14.7 years from a retrospective cohort of 104 patients who underwent PET imaging before curative surgery. PET-Axillary|Sternal was classified as PET-positive if hypermetabolism was visualized in ipsilateral nodal axillary and/or sternal region, else as PET-negative. The differences of 15 years restricted mean survival time ∆RMST according to PET and LNR were computed from Kaplan-Meier overall survival. The effect of PET and other patients' characteristics was analyzed through rankit normalization, which provides with Cox regression the Royston-Sauerbrei D measure of separation to compare the characteristics (0 indicating no prognostic value). Multivariate analysis of the normalized characteristics used stepwise selection with the Akaike information criterion.

RESULTS

In Kaplan-Meier analysis, LNR > 0.20 versus ≤ 0.20 showed ∆RMST = 3.4 years, P = 0.003. PET-Axillary|Sternal positivity versus PET-negative showed a ∆RMST = 2.6 years, P = 0.008. In Cox univariate analyses, LNR appeared as topmost prognostic separator, D = 1.50, P < 0.001. PET ranked below but was also highly significant, D = 1.02, P = 0.009. In multivariate analyses, LNR and PET-Axillary|Sternal were colinear and mutually exclusive. PET-Axillary|Sternal improved as prognosticator in a model excluding lymph nodes, yielding a normalized hazard ratio of 2.44, P = 0.062.

CONCLUSION

Pathological lymph node assessment remains the gold standard of prognosis. However, PET appears as a valuable surrogate in univariate analysis at 15-year follow-up. There was a trend towards significance in multivariate analysis that warrants further investigation.

The role of axillary reverse mapping in intraoperative nodal palpation during sentinel lymph node biopsy

Intraoperative nodal palpation in the axilla is a mandatory part of sentinel lymph node biopsy. However, there is no consensus regarding the definition of suspicious palpable node. The sampling rate and involvement rate of suspicious palpable nodes are inconsistent. We hypothesized that axillary reverse mapping is helpful to select suspicious palpable sentinel lymph nodes more accurately. Patients with clinically negative nodes underwent sentinel lymph node biopsy with intraoperative nodal palpation and axillary reverse mapping. Blue and hot nodes were removed as sentinel lymph nodes. Suspicious palpable nodes that were neither blue nor hot were removed as palpable sentinel lymph nodes. Nodes around blue and hot sentinel lymph node were incidentally removed as para-sentinel lymph nodes. Fluorescent nodes were considered axillary reverse mapping nodes. Patients with positive sentinel lymph node underwent axillary lymph node dissection. Palpable sentinel lymph nodes and para-sentinel lymph nodes were removed in 130 (15%) of 850 patients with clinically negative nodes. Although palpable sentinel lymph nodes and para-sentinel lymph nodes were involved in 19 (15%) of 130 patients, fluorescent palpable sentinel lymph nodes were involved only in 2 patients and fluorescent para-sentinel lymph nodes were not involved. When excluding fluorescent palpable sentinel lymph nodes and para-sentinel lymph nodes, the sampling rate of suspicious palpable nodes significantly decreased (15% vs. 5%, p < 0.01) and the involvement rate of palpable sentinel lymph nodes significantly increased (15% vs. 31%, p < 0.05). Axillary reverse mapping is helpful to avoid an unnecessary removal of palpable nodes without metastases.

Regional Lymph Node Involvement Among Patients With De Novo Metastatic Breast Cancer

IMPORTANCE

Regional nodal irradiation (RNI) for node-positive breast cancer reduces distant metastases and improves survival, albeit with limited reduction in regional nodal recurrences. The mechanism by which RNI robustly reduces distant metastases while modestly influencing nodal recurrences (ie, the presumed target of RNI) remains unclear.

OBJECTIVE

To determine whether some distant metastases putatively arise from occult regional nodal disease and whether regional recurrences otherwise remain largely undetected until an advanced cancer presentation.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study examined patients presenting with de novo stage IV breast cancer to the Memorial Sloan Kettering Cancer Center in New York, New York, from 2006 to 2018. Medical records were reviewed to ascertain clinicopathological parameters, including estrogen receptor status and survival. Pretreatment positron emission tomography-computed tomography (PET-CT) imaging was reviewed to ascertain the extent of regional nodal involvement at metastatic diagnosis using standard nodal assessment criteria. A subset underwent regional lymph node biopsy for diagnostic confirmation and served to validate the radiographic nodal assessment. Data analysis was performed from October 2019 to February 2020.

EXPOSURES

Untreated metastatic breast cancer.

MAIN OUTCOME AND MEASURES

The primary outcome was the likelihood of regional nodal involvement at the time of metastatic breast cancer presentation and was determined by reviewing pretreatment PET-CT imaging and lymph node biopsy findings.

RESULTS

Among 597 women (median [interquartile range] age, 53 [44-65] years) with untreated metastatic breast cancer, 512 (85.8%) exhibited regional lymph node involvement by PET-CT or nodal biopsy, 509 (85%) had involvement of axillary level I, 328 (55%) had involvement in axillary level II, 136 (23%) had involvement in axillary level III, 101 (17%) had involvement in the supraclavicular fossa, and 96 (16%) had involvement in the internal mammary chain. Lymph node involvement was more prevalent among estrogen receptor-negative tumors (92.4%) than estrogen receptor-positive tumors (83.6%). Nodal involvement at the time of metastatic diagnosis was not associated with overall survival.

CONCLUSIONS AND RELEVANCE

These findings suggest that a majority of patients with de novo metastatic breast cancer harbor regional lymph node disease at presentation, consistent with the hypothesis that regional involvement may precede metastatic dissemination. This is in alignment with the findings of landmark trials suggesting that RNI reduces distant recurrences. It is possible that this distant effect of RNI may act via eradication of occult regional disease prior to systemic seeding. The challenges inherent in detecting isolated nodal disease (which is typically asymptomatic) may account for the more modest observed benefit of RNI on regional recurrences. Alternative explanations of nodal involvement that arises concurrently or after metastatic dissemination remain possible, but do not otherwise explain the association of RNI with distant recurrence.

Can We Identify or Exclude Extensive Axillary Nodal Involvement in Breast Cancer Patients Preoperatively?

Background

Breast cancer treatment has rapidly changed in the last few years. Particularly, treatment of patients with axillary nodal involvement has evolved after publication of several randomized clinical trials. Omitting axillary lymph node dissection in selected early breast cancer patients with one or two positive sentinel nodes did not compromise overall survival nor regional disease control in these trials. Hence, either excluding or identifying extensive axillary nodal involvement becomes increasingly important.

Purpose

To evaluate whether the current diagnostic modalities can accurately identify or exclude extensive axillary nodal involvement. Evaluated modalities were axillary ultrasound, ultrasound-guided needle biopsy, MRI, and PET/CT.

Methods

A literature search was performed in the Cochrane Library, EMBASE, and PubMed databases up to June 2019. The search strategy included terms for breast cancer, lymph nodes, and the different imaging modalities. Only articles that reported pathological N-stage or the total number of positive axillary lymph nodes were considered for inclusion. Studies with patients undergoing neoadjuvant systemic therapy were excluded.

Conclusion

There is no evidence that any of the current preoperative axillary imaging modalities can accurately exclude or identify breast cancer patients with extensive nodal involvement. Both negative PET/CT and negative MRI scans (with gadolinium-based contrast agents) are promising in excluding extensive nodal involvement. Larger studies should be performed to strengthen this conclusion. False-negative rates of axillary ultrasound and ultrasound-guided needle biopsy are too high to rely on negative results of these modalities in excluding extensive nodal involvement.

A clinical compilation of lymph node pathologies comparing the diagnostic performance of biopsy methods

PURPOSE

It is critical to obtain sufficient tissue, both in quality and quantity, in biopsy applications for histopathological review. Our aim was to compare fine-needle aspiration cytology (FNAC) and core needle biopsy (CNB) techniques in terms of their diagnostic performance in lymph node biopsies. This was a clinical compilation, and histopathological results from biopsies were also evaluated.

METHODS

A total of 242 patients and 246 lymph nodes were prospectively evaluated. All histopathologic specimens were obtained through ultrasonography-guided biopsies performed at our institute between April 2015 and October 2017. Histopathological results were grouped according to diagnostic performance, and the mean performance scores of the two methods were compared.

RESULTS

For FNAC, the mean diagnostic score was calculated to be 1.63, whereas for CNB, the mean diagnostic score was calculated to be 1.89. The difference between diagnostic scores of the two techniques was statistically significant (p < 0.01).

CONCLUSION

We recommend that interventional radiologists perform vacuum-assisted biopsies if there are no financial hindrances or evidence of psychological issues in patients. We recommend this not only for lymph nodes of malignant appearance but also for those that appear benign.

Role of Contrast-Enhanced Sonography in the Evaluation of Axillary Lymph Nodes in Breast Carcinoma: A Monocentric Study

OBJECTIVES

To evaluate the diagnostic performance of contrast-enhanced sonography for characterization of the lymph node status (metastatic or not) in patients with breast carcinomas by comparison with sentinel lymph node biopsy.

METHODS

From January to August 2015, 50 female patients with a histologic diagnosis of invasive breast carcinoma were prospectively examined by ipsilateral axillary contrast-enhanced sonography. The test was performed by a single radiologist using an ultrasound system with a broadband 8-12-MHz, 38-mm high-resolution linear transducer. For the target lymph node, we chose a node with a sonographic pattern that was suspicious for malignancy: ie, a longitudinal-to-transverse diameter ratio of less than 2, absence of a central hyperechogenic hilum, or both. In cases with a lack of sonographic signs of malignancy, we evaluated the node with the maximal transverse diameter. Nodes were considered malignant in cases with total absence of contrast enhancement and in those with enhancement alterations. Within 1 week, all patients underwent sentinel lymph node biopsy, followed by a histologic test.

RESULTS

The histologic test showed benignity in 22 of 50 sentinel lymph nodes, whereas 28 were metastatic. Among the 22 patients with negative biopsy results, contrast-enhanced sonography showed 18 concordances and 4 false-positives results; among the 28 with positive biopsy results, contrast-enhanced sonography obtained 100% correct characterizations of the axillary status. The sensitivity, specificity, and accuracy were 100%, 82%, and 92%, respectively.

CONCLUSIONS

Contrast-enhanced sonography appears to be a method with high accuracy for characterization of axillary lymph nodes, very close to the reference-standard sentinel lymph node biopsy. This technique seems to have overall high sensitivity.