Improving Prediction Accuracy of Residual Axillary Lymph Node Metastases in Node-Positive Triple-Negative Breast Cancer: A Radiomics Analysis of Ultrasound-Guided Clip Locations Using the SHAP Method

RATIONALE AND OBJECTIVES

To construct a radiomics nomogram derived from multiparametric ultrasound (US) imaging using the SHapley Additive exPlanations (SHAP) method for the accurate identification of residual axillary lymph node metastases post-neoadjuvant chemotherapy (NAC) among patients with triple-negative breast cancer (TNBC).

METHODS

A total of 405 consecutive patients with pathologically confirmed TNBC between 2016 and 2023 were recruited in the study and were divided into training (n = 284) and validation cohorts (n = 121). Radiomics features capturing detailed tumor characteristics were extracted from pre-NAC gray-scale US images at the locations of US-guided clip placement. The least absolute shrinkage and selection operator and the maximum relevance minimum redundancy algorithm were employed to identify key features and formulate the radiomics signature (RS). A nomogram based on US radiomics was then constructed using multivariable logistic regression analysis. The predictive efficacy of this model was evaluated through receiver operating characteristic curve analysis, calibration assessment, and decision curve analysis. SHAP summary plots were used to visualize the distribution of SHAP values across all features.

RESULTS

The nomogram integrates clinical and US characteristics with RS, yielded optimal AUC of 0.922 (95% CI, 0.890-0.954) in the training cohort, 0.904 (95% CI, 0.853-0.955) in the validation cohort. The calibration and decision curves confirmed favorable calibration and clinical value of the nomogram. SHAP provided further insight into the contributions of each feature to the model's outcomes.

CONCLUSION

The combined multiparametric US based radiomics nomogram plays a potential role in predicting residual axillary lymph node metastases after NAC in TNBCs.

Validation of prognostic and predictive value of total tumoral load after primary systemic therapy in breast cancer using OSNA assay

PURPOSE

This study aimed to validate the classification of breast cancer (BC) patients in progression risk groups based on total tumor load (TTL) value to predict lymph node (LN) affectation after neo-adjuvant systemic therapy (NAST) obtained in the NEOVATTL study.

METHODS/PATIENTS

This was an observational, retrospective, international, multicenter study including patients with infiltrating BC who received NAST followed by sentinel lymph node biopsy (SLNB) analyzed with one-step nucleic acid amplification (OSNA) from nine Spanish and two Italian hospitals. Patients were classified into three groups according to the progression risk, measured as disease-free survival (DFS), based on TTL values (> 250, 250-25,000, and > 25,000 copies/μL). The previous (NEOVATTL study) Cox regression model for prognosis was validated using prognostic index (PI) and Log ratio test (LRT) analyses; the value of TTL for axillary non-SLN affectation was assessed using receiver operating characteristic (ROC) curves.

RESULTS

We included 263 patients with a mean age of 51.4 (± SD 10.5) years. Patients with TTL > 25,000 copies/μL had a shorter DFS (HR 3.561 [95% CI 1.693-7.489], p = 0.0008 vs. TTL ≤ 25,000). PI and LRT analyses showed no differences between the two cohorts (p = 0.2553 and p = 0.226, respectively). ROC analysis showed concordance between TTL and non-SLN involvement (area under the curve 0.828), with 95.7% sensitivity and 92.9% specificity at a TTL cut-off of > 15,000 copies/μL.

CONCLUSIONS

In BC patients who had received NAST and underwent SLNB analysis using OSNA, a TTL value of > 25,000 copies/μL was associated with a higher progression risk and > 15,000 copies/μL was predictive of non-SLN involvement.

The role of irradiation in the management of the axilla in early breast cancer patients

The need for axillary radiotherapy in patients with invasive breast cancer (IBC) has been a topic of great debate in the last decade. Management of the axilla has evolved significantly over the past four decades with a trend towards de-escalation of surgical interventions and the aim of reducing morbidity and enhancing QOL without compromising long-term oncology outcomes. This review article will address the role of axillary irradiation with a focus on the omission of completion axillary lymph node dissection in selected patients with sentinel lymph node (SLN) positive early breast cancer (EBC) with reference to current guidelines based on evidence to date.

Value of total tumor load as a clinical and pathological factor in the prognosis of breast cancer patients receiving neoadjuvant treatment. Comparison of three populations with three different surgical approaches: NEOVATTL Pro 3 Study

PURPOSE

This study aimed to compare the prognosis in terms of disease-free survival (DFS) in three populations of women with breast cancer (BC) treated with neoadjuvant systemic treatment (NAST) in which axillary lymph node dissection (ALND) was performed based on different total tumor load (TTL) thresholds in the sentinel nodes.

METHODS

This was an observational, retrospective study carried out in three Spanish centers. Data from patients with infiltrating BC who underwent BC surgery after NAST and intraoperative sentinel lymph node biopsy (SLNB) performed by One Step Nucleic acid Amplification (OSNA) technique during 2017 and 2018 were analyzed. ALND was performed according to the protocol of each center, based on three different TTL cut-offs (TTL > 250, TTL > 5000, and TTL > 15,000 CK19-mRNA copies/μL for centers 1, 2, and 3, respectively).

RESULTS

A total of 157 BC patients were included in the study. No significant differences in DFS were observed between centers (Hazard ratio [HR] center 2 vs 1: 0.77; p = 0.707; HR center 3 vs 1: 0.83; p = 0.799). Patients with ALND had a shorter DFS (HR 2.43; p = 0.136), albeit not statistically significant. Patients with a triple negative subtype had a worse prognosis than those with other molecular subtypes (HR 2.82; p = 0.056).

CONCLUSION

No significant differences in DFS were observed between three centers with different surgical approaches to ALND based on different TTL cut-offs in patients with BC after NAST. These results suggest that restricting ALND to those patients with TTL ≥ 15,000 copies/μL is a reliable approximation, avoiding unnecessary morbidities caused by ALND.

Role and evaluation of pathologic response in early breast cancer specimens after neoadjuvant therapy: consensus statement

Pathologic evaluation of early breast cancer after neoadjuvant therapy is essential to provide prognostic information based on tumor response to treatment (pathologic complete response [pCR] or non-pCR) and to inform therapy decisions after surgery. To harmonize the pathologist’s handling of surgical specimens after neoadjuvant therapy, a panel of experts in breast cancer convened to developed a consensus on six main topics: (1) definition of pCR, (2) required clinical information, (3) gross examination and sampling, (4) microscopic examination, (5) evaluation of lymph node status, and (6) staging of residual breast tumor. The resulting consensus statements reported in this document highlight the role of an accurate evaluation of tumor response and define the minimum requirements to standardize the assessment of breast cancer specimens after neoadjuvant therapy.

Lymph nodal radiotherapy in breast cancer: what are the unresolved issues?

Introduction: Sentinel lymph node biopsy (SLNB) is the gold standard in invasive breast cancer. Axillary dissection (ALND) is controversial in some presentations.Areas covered: Key questions were formulated and explored focused on four different scenarios in adjuvant axillary radiation management in early and locally advanced breast cancer. Answers to these questions were searched in MEDLINE, PubMed from June 1946 to August 2020. Clinical trials, retrospective studies, international guidelines, meta-analysis, and reviews were explored.Expert opinion: Analysis according to biological disease characteristics is necessary to establish the impact of ALND avoidance in unexpectedly positive SLNB (pN1) in cN0 patients. A low-risk probability of axillary recurrence was observed if axillary radiotherapy (ART) or ALND were offered without impact on outcomes. Adjuvant RNI in pT1-3 pN1 treated with mastectomy or BCS should be proposed in unfavorable disease and risk factors. In ycN0 after NACT, SLNB can be offered in selected cases or ALND should be performed. After SLNB post-NACT (ypN1), ALND and adjuvant radiotherapy are mandatory.

Can one stop nucleic acid sampling (OSNA) predict nodal positivity following neoadjuvant chemotherapy? A prospective cohort study of 293 patients

Until recently, axillary node clearance had long been the standard of care in patients with axillary node-positive disease. One stop nucleic acid sampling (OSNA) has been used to guide intraoperative decision-making regarding suitability for axillary node clearance (ANC). The aim of this study is to evaluate the use of OSNA following neoadjuvant chemotherapy (NACT) and whether it can predict lymph node burden in ANC. A single center, prospective cohort study was performed on 297 patients having OSNA between 2016 and 2019. Patients were sub-classified according to node positivity at diagnosis and those treated with NACT and outcomes included copy number and lymph node harvest. Axillary complete pathological response was observed in 24/36 patients (67%) following NACT. 14/16 patients (87%) having axillary node clearance had axillary node disease limited to 4 nodes. OSNA copy numbers were significantly higher in patients showing disease progression following NACT. Overall, 73% of patients with lymph node positivity at diagnosis could be successfully treated with a combination of NACT and lymph node excision of four nodes. De-escalating axillary surgical treatment to resection of four nodes following NACT may be effective in balancing oncological resection and limiting treatment morbidity. ONSA can correctly identify patients experiencing disease progression who would benefit from traditional three-level ANC.

Individualized Prediction of Survival Benefit from Postmastectomy Radiotherapy for Patients with Breast Cancer with One to Three Positive Axillary Lymph Nodes

PURPOSE

There still exist some arguments regarding the use of postmastectomy radiotherapy (PMRT) for patients with breast cancer carrying one to three positive axillary lymph nodes considering the heterogeneity of this cohort. Here, we developed a prognostic nomogram to estimate the probability of long-term outcome in patients receiving or not receiving PMRT in order to assist in making individually locoregional treatment decisions for this particular cohort.

METHODS

Altogether, 20,336 women, aged 18 to 80 years, diagnosed with breast cancer, and carrying one to three positive nodes were identified in the Surveillance, Epidemiology, and End Results (SEER) database. We applied multivariant Cox hazard model to determine the impact of covariates on disease-specific survival (DSS) and overall survival (OS). Then, the nomogram was built accordingly. Internal and external validations were performed to examine the accuracy of nomograms.

RESULTS

Age of diagnosis, tumor grade, size, estrogen and progesterone receptor status, and number of positive nodes were independent factors of DSS and OS in the multivariate analysis. Incorporating these factors into the constructed nomogram showed high accuracy when predicting 5- and 10-year survival, with internally and externally bootstrap-corrected concordance indexes in the range of 0.6 to 0.8.

CONCLUSION

Besides the number of involved nodes, extra variables existed as predictors of survival outcomes in this cohort; therefore, the recommendation of PMRT or no PMRT requires comprehensive consideration. This clinically validated nomogram provided a useful tool that could aid decision making by estimating DSS and OS benefits from PMRT, useful in predicting 5- and 10-year DSS and OS for patients with one to three positive nodes after mastectomy.

IMPLICATIONS FOR PRACTICE

This study evaluated population-based data to identify prognostic factors associated with patients with breast cancer with one to three lymph nodes and help clinicians to weigh the benefit of postmastectomy radiotherapy (PMRT). Surveillance, Epidemiology, and End Results (SEER) data were used to develop a prognostic nomogram to predict the likelihood of long-term survival with and without PMRT in order to optimize the individual locoregional control strategy for this particular cohort. This clinically validated nomogram provides a useful tool to predict 5- and 10-year disease-specific survival and overall survival for patients with one to three positive nodes and can aid tailored clinical decision making by estimating predicted benefit from PMRT.

Axillary Surgery Following Neoadjuvant Chemotherapy - Multidisciplinary Guidance From the Association of Breast Surgery, Faculty of Clinical Oncology of the Royal College of Radiologists, UK Breast Cancer Group, National Coordinating Committee for Breast Pathology and British Society of Breast Radiology

AIMS

These multidisciplinary guidelines aim to provide clinically helpful, evidence-based recommendations on the surgical management of the axilla in patients who have received neo-adjuvant chemotherapy for early breast cancer.

MATERIALS & METHODS

Following a review of published evidence, a writing group representing all disciplines quorate within a breast cancer multidisciplinary meeting prepared the guidelines.

KEY RECOMMENDATIONS

In patients presenting with clinically node negative axillae, sentinel node biopsy (SNB) may be performed prior to or on completion of neo-adjuvant chemotherapy (NACT). In patients presenting with clinically node positive axillae, SNB may be safely considered following completion of NACT. Four nodes should be removed with dual mapping. If evidence of complete pathological response of previous metastases is seen, axillary radiotherapy may be offered. If residual cancer (isolated tumour cells, micro- or macrometastes) is seen within the SNB, offer axillary node dissection.