Minimally Invasive Complete Response Assessment of the Breast After Neoadjuvant Systemic Therapy for Early Breast Cancer (MICRA trial): Interim Analysis of a Multicenter Observational Cohort Study

Utility of Axillary Staging in Older Patients with HER2-Positive Breast Cancer

BACKGROUND

The utility of sentinel lymph node biopsy (SLNB) in older patients remains controversial. Advancements in human epidermal growth factor receptor 2 (HER2)-directed therapy have revolutionized disease response rates and prognosis, supporting efforts to re-evaluate the utility of SLNB. We aimed to assess the differences in treatment and overall survival (OS) in older patients with HER2-positive breast cancer based on SLNB.

METHODS

Using the National Cancer Database (2010-2020), patients ≥ 70 years of age diagnosed with cT1-2/cN0/M0, HER2-positive breast cancer were identified. Logistic regression assessed associations with SLNB, systemic therapy, and radiation. Cox proportional hazard models were used to identify factors associated with OS. Analyses were stratified by treatment sequence, i.e. upfront surgery or neoadjuvant therapy (NAT) followed by surgery.

RESULTS

Of the 17,609 patients included, 94% underwent upfront surgery (n = 16,492) and the remaining underwent NAT (n = 1117). Those who underwent SLNB were more likely to receive adjuvant therapy, irrespective of nodal status {upfront surgery/systemic therapy (odds ratio [OR] 2.82, 95% confidence interval [CI] 2.17-3.67); upfront surgery/radiation (OR 3.97, 95% CI 3.03-5.21); NAT/radiation (OR 5.69, 95% CI 1.83-17.69)}. The breast pathologic complete response (pCR) rate was highest among the hormone receptor (HR)-negative/HER2-positive subtype (50.0%), of which none were found to be ypN+. Comorbidity burden was associated with significantly lower rates of adjuvant systemic therapy and worse OS.

CONCLUSIONS

Patients who underwent SLNB, regardless of pN status, were more likely to receive adjuvant therapy. Nodal positivity is exceedingly rare for patients with a breast pCR following NAT, especially among the HR-negative/HER2-positive subtype. It is reasonable to consider omission of SLNB in select subgroups of older patients with HER2-positive breast cancer.

Diffusion-weighted imaging in addition to contrast-enhanced MRI in identifying complete response in HER2-positive breast cancer

OBJECTIVES

The aim of this study is to investigate the added value of diffusion-weighted imaging (DWI) to dynamic-contrast enhanced (DCE)-MRI to identify a pathological complete response (pCR) in patients with HER2-positive breast cancer and radiological complete response (rCR).

MATERIALS AND METHODS

This is a single-center observational study of 102 patients with stage I-III HER2-positive breast cancer and real-world documented rCR on DCE-MRI. Patients were treated between 2015 and 2019. Both 1.5 T/3.0 T single-shot diffusion-weighted echo-planar sequence were used. Post neoadjuvant systemic treatment (NST) diffusion-weighted images were reviewed by two readers for visual evaluation and ADCmean. Discordant cases were resolved in a consensus meeting. pCR of the breast (ypT0/is) was used to calculate the negative predictive value (NPV). Breast pCR-percentages were tested with Fisher's exact test. ADCmean and ∆ADCmean(%) for patients with and without pCR were compared using a Mann-Whitney U-test.

RESULTS

The NPV for DWI added to DCE is 86% compared to 87% for DCE alone in hormone receptor (HR)-/HER2-positive and 67% compared to 64% in HR-positive/HER2-positive breast cancer. Twenty-seven of 39 non-rCR DWI cases were false positives. In HR-negative/HER2-positive breast cancer the NPV for DCE MRI differs between MRI field strength (1.5 T: 50% vs. 3 T: 81% [p = 0.02]). ADCmean at baseline, post-NST, and ∆ADCmean were similar between patients with and without pCR.

CONCLUSION

DWI has no clinically relevant effect on the NPV of DCE alone to identify a pCR in early HER2-positive breast cancer. The added value of DWI in HR-positive/HER2-positive breast cancer should be further investigated taken MRI field strength into account.

CLINICAL RELEVANCE STATEMENT

The residual signal on DWI after neoadjuvant systemic therapy in cases with early HER2-positive breast cancer and no residual pathologic enhancement on DCE-MRI breast should not (yet) be considered in assessing a complete radiologic response.

KEY POINTS

Radiologic complete response is associated with a pathologic complete response (pCR) in HER2+ breast cancer but further improvement is warranted. No relevant increase in negative predictive value was observed when DWI was added to DCE. Residual signal on DW-images without pathologic enhancement on DCE-MRI, does not indicate a lower chance of pCR.

Clinical applications of next-generation sequencing-based ctDNA analyses in breast cancer: defining treatment targets and dynamic changes during disease progression

The advancements in the detection and characterization of circulating tumor DNA (ctDNA) have revolutionized precision medicine and are likely to transform standard clinical practice. The non-invasive nature of this approach allows for molecular profiling of the entire tumor entity, while also enabling real-time monitoring of the effectiveness of cancer therapies as well as the identification of resistance mechanisms to guide targeted therapy. Although the field of ctDNA studies offers a wide range of applications, including in early disease, in this review we mainly focus on the role of ctDNA in the dynamic molecular characterization of unresectable locally advanced and metastatic BC (mBC). Here, we provide clinical practice guidance for the rapidly evolving field of molecular profiling of mBC, outlining the current landscape of liquid biopsy applications and how to choose the right ctDNA assay. Additionally, we underline the importance of exploring the clinical relevance of novel molecular alterations that potentially represent therapeutic targets in mBC, along with mutations where targeted therapy is already approved. Finally, we present a potential roadmap for integrating ctDNA analysis into clinical practice.

A nomogram to predict the pathological complete response in patients with breast cancer based on the TILs-US score

BACKGROUND

The tumor-infiltrating lymphocytes-ultrasonography score is a calculation system for predicting lymphocyte-predominant breast cancers in surgical specimens. A nomogram based on the tumor-infiltrating lymphocytes-ultrasonography score was developed to predict the pathological complete response in breast cancer treated with neoadjuvant chemotherapy.

METHODS

A retrospective evaluation was conducted on 118 patients with breast cancer treated with neoadjuvant chemotherapy at Hiroshima University Hospital. Tumor-infiltrating lymphocytes-ultrasonography scores ≥4 were classified as high. A nomogram was developed using a stepwise logistic regression model for pathological complete response (ypT0 ypN0), based on the smallest Akaike information criterion. The predictive ability and clinical usefulness of the nomogram were also evaluated.

RESULTS

Among 118 patients, 34 (28.8%) achieved a pathological complete response, and 52 (44.1%) exhibited high tumor-infiltrating lymphocytes-ultrasonography. In multivariate logistic regression analysis, high tumor-infiltrating lymphocytes-ultrasonography (odds ratio, 6.01; P < 0.001), clinical complete response (odds ratio, 4.83; P = 0.004) and hormone receptor (odds ratio, 3.48; P = 0.038) were independent predictors of pathological complete response. A nomogram based on tumor-infiltrating lymphocytes-ultrasonography score, clinical complete response, hormone receptor and clinical N status was developed. The nomogram showed an area under the curve of 0.831 and a bias-corrected area under the curve of 0.809. The calibration plot showed a good fit between the expected and actual pathological complete response values. Decision curve analysis also showed the clinical utility of the nomogram for predicting pathological complete responses.

CONCLUSIONS

A nomogram based on the tumor-infiltrating lymphocytes-ultrasonography score exhibited a favorable predictive ability for pathological complete response in patients with breast cancer, which can be useful in predicting the residual disease status after neoadjuvant chemotherapy.

Omission of Breast Surgery in Exceptional Responders

Breast cancer management has transformed significantly over the last decades, primarily through the integration of neoadjuvant systemic therapy (NST) and the evolving understanding of tumor biology, enabling more tailored treatment strategies. The aim of this review is to critically present the historical context and contemporary evidence surrounding the potential of omission of surgery post-NST, focusing on exceptional responders who have achieved a pathologic complete response (pCR). Identifying these exceptional responders before surgery remains a challenge, however standardized image-guided biopsy may allow optimized patient selection. The safety and feasibility of omitting breast and axillary surgeries in these exceptional responders are explored in ongoing clinical trials and the reported preliminary results appear promising. Moreover, understanding patient and physician perspectives regarding the potential elimination of surgery post-NST is integral. While some patients express a preference to omit or minimize surgery, the majority of healthcare providers are intrigued by the prospect of avoiding surgical interventions and endorse further research in this field.

A nomogram for predicting pathologic node negativity after neoadjuvant chemotherapy in breast cancer patients: a nationwide, multicenter retrospective cohort study (CSBrS-012)

Purpose

This study aimed to investigate the factors associated with pathologic node-negativity (ypN0) in patients who received neoadjuvant chemotherapy (NAC) to develop and validate an accurate prediction nomogram.

Methods

The CSBrS-012 study (2010-2020) included female patients with primary breast cancer treated with NAC followed by breast and axillary surgery in 20 hospitals across China. In the present study, 7,711 eligible patients were included, comprising 6,428 patients in the primary cohort from 15 hospitals and 1,283 patients in the external validation cohort from five hospitals. The hospitals were randomly assigned. The primary cohort was randomized at a 3:1 ratio and divided into a training set and an internal validation set. Univariate and multivariate logistic regression analyses were performed on the training set, after which a nomogram was constructed and validated both internally and externally.

Results

In total, 3,560 patients (46.2%) achieved ypN0, and 1,558 patients (20.3%) achieved pathologic complete response in the breast (bpCR). A nomogram was constructed based on the clinical nodal stage before NAC (cN), ER, PR, HER2, Ki67, NAC treatment cycle, and bpCR, which were independently associated with ypN0. The area under the receiver operating characteristic curve (AUC) for the training set was 0.80. The internal and external validation demonstrated good discrimination, with AUCs of 0.79 and 0.76, respectively.

Conclusion

We present a real-world study based on nationwide large-sample data that can be used to effectively screen for ypN0 to provide better advice for the management of residual axillary disease in breast cancer patients undergoing NAC.

Breast surgery after neoadjuvant systemic therapy

For patients with operable breast cancer, neoadjuvant systemic therapy (NST) can be used to downstage the primary tumor in the breast and to facilitate breast-conserving surgery (BCS) in patients with large tumors who desire breast conservation. Rates of breast pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) are highest in patients with triple-negative and human epidermal growth factor receptor 2 (HER2) positive (HER2+) disease; however, achieving pCR is not necessary for successful downstaging and avoidance of mastectomy, and rates of conversion to BCS-eligibility are high across all receptor subtypes. Neoadjuvant endocrine therapy (NET) can be used instead of NAC in postmenopausal patients with hormone receptor positive (HR+)/HER2 negative (HER2-) breast cancer to downstage the breast, particularly when the patient has no clear indication for systemic chemotherapy, but desires breast conservation. In patients treated with NET, rates of conversion to BCS-eligibility are similar to rates observed with NAC. The oncologic safety of BCS after NAC and NET has been established in prospective trials, and local recurrence (LR) rates are acceptably low provided negative surgical margins can be obtained. Investigation is under way to determine the feasibility and safety of omitting breast surgery in patients with responsive subtypes who have no residual invasive or in situ disease identified on post-treatment tumor bed biopsies; however, the significant risk of missing residual disease-which may impact selection of adjuvant systemic therapy-may preclude future adoption of this approach.

Omission of Breast Surgery in Predicted Pathologic Complete Response after Neoadjuvant Systemic Therapy: A Multicenter, Single-Arm, Non-inferiority Trial

PURPOSE

Advances in chemotherapeutic and targeted agents have increased pathologic complete response (pCR) rates after neoadjuvant systemic therapy (NST). Vacuum-assisted biopsy (VAB) has been suggested to accurately evaluate pCR. This study aims to confirm the non-inferiority of the 5-year disease-free survival of patients who omitted breast surgery when predicted to have a pCR based on breast magnetic resonance imaging (MRI) and VAB after NST, compared with patients with a pCR who had undergone breast surgery in previous studies.

METHODS

The Omission of breast surgery for PredicTed pCR patients wIth MRI and vacuum-assisted bIopsy in breaST cancer after neoadjuvant systemic therapy (OPTIMIST) trial is a prospective, multicenter, single-arm, non-inferiority study enrolling in 17 tertiary care hospitals in the Republic of Korea. Eligible patients must have a clip marker placed in the tumor and meet the MRI criteria suggesting complete clinical response (post-NST MRI size ≤ 1 cm and lesion-to-background signal enhancement ratio ≤ 1.6) after NST. Patients will undergo VAB, and breast surgery will be omitted for those with no residual tumor. Axillary surgery can also be omitted if the patient was clinically node-negative before and after NST and met the stringent criteria of MRI size ≤ 0.5 cm. Survival and efficacy outcomes are evaluated over five years.

DISCUSSION

This study seeks to establish evidence for the safe omission of breast surgery in exceptional responders to NST while minimizing patient burden. The trial will address concerns about potential undertreatment due to false-negative results and recurrence as well as improved patient-reported quality of life issues from the omission of surgery. Successful completion of this trial may reshape clinical practice for certain breast cancer subtypes and lead to a safe and less invasive approach for selected patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05505357. Registered on August 17, 2022. Clinical Research Information Service Identifier: KCT0007638. Registered on July 25, 2022.

Axillary lymph node dissection in triple-negative or HER2-positive breast cancer patients with clinical N2 achieving pathological complete response after neoadjuvant therapy: Is it necessary?

AIM

This study aims to identify suitable candidates for axillary sentinel lymph node biopsy (SLNB) or targeted axillary dissection (TAD) among clinical N2 (cN2) triple-negative (TN) or HER2 positive (HER2+）breast cancer patients following neoadjuvant therapy（NAT）.

BACKGROUND

Despite the substantial axillary burden in cN2 breast cancer patients, high pathological response rates can be achieved with NAT in TN or HER2+ subtypes, thus enabling potential downstaging of axillary surgery.

METHODS

A retrospective analysis was conducted on data from the CSBrS-012 study, screening 709 patients with initial cN2, either HER2+ or TN subtype, from January 1, 2010 to December 31, 2020. The correlation between axillary pathologic complete response (pCR) (yPN0) and breast pCR was examined.

RESULTS

Among the 177 cN2 patients who achieved breast pCR through NAT, 138 (78.0 %) also achieved axillary pCR. However, in the 532 initial clinical N2 patients who did not achieve breast pCR, residual axillary lymph node metastasis persisted in 77.4 % (412/532) of cases. The relative risk of residual axillary lymph node metastasis in patients who did not achieve breast pCR was 12.4 (8.1-19.1), compared to those who did achieve breast pCR, P < 0.001.

CONCLUSION

For cN2 TN or HER2+ breast cancer patients who achieve breast pCR following NAT, consideration could be given to downstaging and performing an axillary SLNB or TAD.

Nodal positivity in patients with clinically and radiologically node-negative breast cancer treated with neoadjuvant chemotherapy: multicentre collaborative study

BACKGROUND

The necessity of performing a sentinel lymph node biopsy in patients with clinically and radiologically node-negative breast cancer after neoadjuvant chemotherapy has been questioned. The aim of this study was to determine the rate of nodal positivity in these patients and to identify clinicopathological features associated with lymph node metastasis after neoadjuvant chemotherapy (ypN+).

METHODS

A retrospective multicentre study was performed. Patients with cT1-3 cN0 breast cancer who underwent sentinel lymph node biopsy after neoadjuvant chemotherapy between 2016 and 2021 were included. Negative nodal status was defined as the absence of palpable lymph nodes, and the absence of suspicious nodes on axillary ultrasonography, or the absence of tumour cells on axillary nodal fine needle aspiration or core biopsy.

RESULTS

A total of 371 patients were analysed. Overall, 47 patients (12.7%) had a positive sentinel lymph node biopsy. Nodal positivity was identified in 22 patients (29.0%) with hormone receptor+/human epidermal growth factor receptor 2- tumours, 12 patients (13.8%) with hormone receptor+/human epidermal growth factor receptor 2+ tumours, 3 patients (5.6%) with hormone receptor-/human epidermal growth factor receptor 2+ tumours, and 10 patients (6.5%) with triple-negative breast cancer. Multivariable logistic regression analysis showed that multicentric disease was associated with a higher likelihood of ypN+ (OR 2.66, 95% c.i. 1.18 to 6.01; P = 0.018), whilst a radiological complete response in the breast was associated with a reduced likelihood of ypN+ (OR 0.10, 95% c.i. 0.02 to 0.42; P = 0.002), regardless of molecular subtype. Only 3% of patients who had a radiological complete response in the breast were ypN+. The majority of patients (85%) with a positive sentinel node proceeded to axillary lymph node dissection and 93% had N1 disease.

CONCLUSION

The rate of sentinel lymph node positivity in patients who achieve a radiological complete response in the breast is exceptionally low for all molecular subtypes.

Different approaches to target volume definition and boost delivery in surgery de-escalation clinical trial in breast cancer patients with pathological complete response

PURPOSE

We evaluate various approaches to target volume definition and boost delivery in patients with complete response to neoadjuvant systemic therapy (NST) who were treated by radiotherapy without a surgery.

MATERIALS AND METHODS

A pathological complete response (pCR) was diagnosed in 21 of 27 patients included in "surgery de-escalation" prospective observation study. Clips were placed in the primary tumor volume (PrTV) before NST and during the vacuum aspiration biopsy. Twenty patients with pCR underwent the whole breast irradiation and a boost to the PrTV. High-dose rate brachytherapy (HDRB) was the basic technique for boost delivery. Finally, we identified the value of fused images (computed tomography [CT] before NST with simulation CT), clips and their combination for an accurate boost delivery.

RESULTS

A complete overlap between PrTV on pre-treatment CT with the localization of the clips on simulation CT was mentioned in 10, partial mismatch in three patients. In 12 of these 13 women, HDRB was successfully used for the boost delivery. In five cases we mentioned a marked discrepancy between the PrTV on fused images and the topography of the clips. In other two women we did not find clips on simulation CT. The fused images in five of these seven patients showed anatomical landmarks (scar, fibrosis) used for identification of the gross tumor volume. In all 20 women with pCR (average follow-up of 16.6 months), there were no locoregional recurrences.

CONCLUSION

Combination of the clips with fusion of pre-NST and simulation CTs is important for an accurate boost delivery.

Assessment of Pathological Complete Response Using Vacuum-Assisted Biopsy in Breast Cancer Patients Who Have Clinical and Radiological Complete Response After Neo-Adjuvant Chemotherapy

Background

Any treatment protocol that leads to complete elimination of surgery may lead to a better patient acceptance of breast cancer treatments.

Objectives

We conducted this study to assess the feasibility of preoperative vacuum-assisted biopsies in identifying pathological complete response (pCR) and its accuracy in correlation to final histopathology report (HPR), in an Indian setting.

Methods

This was a prospective study conducted between October 1, 2019, and March 31, 2021. Patients with early breast cancer, estrogen and progesterone receptors negative and either Her2 positive or negative, and who were fit to undergo marker placement at the centre of the tumour and to receive third-generation chemotherapy (4 cycles of 3 weekly doxorubicin and cyclophosphamide followed by 4 cycles of 3 weekly docetaxel) were included in the study. Following the enrolment, a tissue marker was placed at the centre of the tumour and appropriate chemotherapy was started. Patients who achieved clinical complete response were subjected to ultrasound-guided vacuum-assisted biopsy (VAB) from the tumour bed before surgery. Pathology results of the VAB and resected specimen were then compared. Descriptive statistics were used in the study.

Results

Eighteen patients were enrolled in the study, with a mean age of 43.6 ± 9.8 years. However, only 10 were eligible for VAB procedure, and sensitivity and specificity were calculated based on the results of these 10 patients only. Vacuum-assisted biopsy showed sensitivity of 50% and specificity of 100% in identifying pCR. Combination of mammography, ultrasonography, and VAB showed sensitivity of 77.8% and specificity of 66.7% in identifying pCR.

Conclusion

Vacuum-assisted biopsy of tumour bed may not be sensitive enough to eliminate surgery even in patients who have had exceptional response to neo-adjuvant chemotherapy.

89Zr-Trastuzumab PET/CT Imaging of HER2-Positive Breast Cancer for Predicting Pathological Complete Response after Neoadjuvant Systemic Therapy: A Feasibility Study

BACKGROUND

Approximately 20% of invasive ductal breast malignancies are human epidermal growth factor receptor 2 (HER2)-positive. These patients receive neoadjuvant systemic therapy (NAT) including HER2-targeting therapies. Up to 65% of patients achieve a pathological complete response (pCR). These patients might not have needed surgery. However, accurate preoperative identification of a pCR remains challenging. A radiologic complete response (rCR) on MRI corresponds to a pCR in only 73% of patients. The current feasibility study investigates if HER2-targeted PET/CT-imaging using Zirconium-89 (89Zr)-radiolabeled trastuzumab can be used for more accurate NAT response evaluation.

METHODS

HER2-positive breast cancer patients scheduled to undergo NAT and subsequent surgery received a 89Zr-trastuzumab PET/CT both before (PET/CT-1) and after (PET/CT-2) NAT. Qualitative and quantitative response evaluation was performed.

RESULTS

Six patients were enrolled. All primary tumors could be identified on PET/CT-1. Four patients had a pCR and two a pathological partial response (pPR) in the primary tumor. Qualitative assessment of PET/CT resulted in an accuracy of 66.7%, compared to 83.3% of the standard-of-care MRI. Quantitative assessment showed a difference between the SUVR on PET/CT-1 and PET/CT-2 (ΔSUVR) in patients with a pPR and pCR of -48% and -90% (p = 0.133), respectively. The difference in tumor-to-blood ratio on PET/CT-1 and PET/CT-2 (ΔTBR) in patients with pPR and pCR was -79% and -94% (p = 0.133), respectively. Three patients had metastatic lymph nodes at diagnosis that were all identified on PET/CT-1. All three patients achieved a nodal pCR. Qualitative assessment of the lymph nodes with PET/CT resulted in an accuracy of 66.7%, compared to 50% of the MRI.

CONCLUSIONS

NAT response evaluation using 89Zr-trastuzumab PET/CT is feasible. In the current study, qualitative assessment of the PET/CT images is not superior to standard-of-care MRI. Our results suggest that quantitative assessment of 89Zr-trastuzumab PET/CT has potential for a more accurate response evaluation of the primary tumor after NAT in HER2-positive breast cancer.

Is Axillary Staging Obsolete in Early Breast Cancer?

This article reviews the incidence of nodal metastases in early-stage breast cancer and the need for axillary staging to maintain local control in the axilla or to determine the need for adjuvant systemic therapy across the spectrum of patients with breast cancer, and reviews clinical trials addressing this question. At present, sentinel lymph node biopsy should be omitted in women age ≥70 years with cT1-2 N0, HR+/HER2- cancers. The importance of nodal status in selecting patients for radiotherapy remains the main reason for axillary staging in younger postmenopausal women with cT1-2N0, HR+/HER2- cancers.

Standardized Definitions for Efficacy End Points in Neoadjuvant Breast Cancer Clinical Trials: NeoSTEEP

PURPOSE

The Standardized Definitions for Efficacy End Points (STEEP) criteria, established in 2007 and updated in 2021 (STEEP 2.0), provide standardized definitions of adjuvant breast cancer (BC) end points. STEEP 2.0 identified a need to separately address end points for neoadjuvant clinical trials. The multidisciplinary NeoSTEEP working group of experts was convened to critically evaluate and align neoadjuvant BC trial end points.

METHODS

The NeoSTEEP working group concentrated on neoadjuvant systemic therapy end points in clinical trials with efficacy outcomes-both pathologic and time-to-event survival end points-particularly for registrational intent. Special considerations for subtypes and therapeutic approaches, imaging, nodal staging at surgery, bilateral and multifocal diseases, correlative tissue collection, and US Food and Drug Administration regulatory considerations were contemplated.

RESULTS

The working group recommends a preferred definition of pathologic complete response (pCR) as the absence of residual invasive cancer in the complete resected breast specimen and all sampled regional lymph nodes (ypT0/Tis ypN0 per AJCC staging). Residual cancer burden should be a secondary end point to facilitate future assessment of its utility. Alternative end points are needed for hormone receptor-positive disease. Time-to-event survival end point definitions should pay particular attention to the measurement starting point. Trials should include end points originating at random assignment (event-free survival and overall survival) to capture presurgery progression and deaths as events. Secondary end points adapted from STEEP 2.0, which are defined from starting at curative-intent surgery, may also be appropriate. Specification and standardization of biopsy protocols, imaging, and pathologic nodal evaluation are also crucial.

CONCLUSION

End points in addition to pCR should be selected on the basis of clinical and biologic aspects of the tumor and the therapeutic agent investigated. Consistent prespecified definitions and interventions are paramount for clinically meaningful trial results and cross-trial comparison.

Accuracy of Tumor Bed Biopsy for Predicting Pathologic Complete Response After Chemotherapy Among Women With Breast Cancer: Complete Responders in the Breast Study

PURPOSE

With the advent of taxanes and targeted agents in neoadjuvant chemotherapy (NACT) for breast cancer, the rates for pathologic complete response (pCR) have been steadily increasing. Surgery in these women serves as a biopsy to confirm or negate a pCR.

METHODS

All newly diagnosed patients with nonmetastatic breast cancer, planned for NACT, were screened. Eligible patients with a complete or near-complete response to NACT as seen on a mammogram and ultrasound (US) were recruited. A magnetic resonance imaging was performed for these patients for documentation. US-guided core biopsies of the tumor bed (Core Bx) using a 14G needle was performed (minimum four in number), and the results were compared with the final histopathology report after surgery for standard performance parameters.

RESULTS

This study recruited 65 women of whom 94% were node-positive, and 60% were hormone receptor-negative. The pCR rate was 41.5% and 53.8% for the whole cohort and the hormone receptor-negative subgroup, respectively. The false-negative rate (FNR) for Core Bx was 42.1% (95% CI, 26.3 to 59.2), with a negative predictive value of 59.0% (95% CI, 42.1 to 74.4). Among the hormone receptor-negative tumors, the FNR was 44.4% (95% CI, 21.5 to 69.2) with a negative predictive value of 70.4% (95% CI, 49.8 to 86.2).

CONCLUSION

The Complete Responders in the Breast study results suggest that ultrasound-guided 14G core needle biopsy of the tumor bed may not be a reliable predictor of pCR in the breast. These results highlight the importance of further research into the omission of surgery in the breast after chemotherapy. This study is registered with Clinical Trials Registry of India (CTRI/2018/01/011122).

Locoregional Treatment for Early-Stage Breast Cancer: Current Status and Future Perspectives

BACKGROUND

The locoregional recurrence of breast cancer has been reduced due to the multidisciplinary approach of breast surgery, systemic therapy and radiation. Early detection and better surgical techniques contribute to an improvement in breast cancer outcomes.

PURPOSE OF REVIEW

The purpose of this review is to have an overview and summary of the current evidence behind the current approaches to the locoregional treatment of breast cancer and to discuss its future direction.

SUMMARY

With improved surgical techniques and the use of a more effective neoadjuvant systemic therapy, including checkpoint inhibitors and dual HER2-directed therapies that lead to a higher frequency of pathologic complete responses and advances in adjuvant radiation therapy, breast cancer patients are experiencing better locoregional control and reduced local and systemic recurrence. De-escalation in surgery has not only improved the quality of life in the majority of breast cancer patients, but also maintained the low risk of recurrence. There are ongoing clinical trials to optimize radiation therapy in breast cancer. More modern radiation technologies are evolving to improve the patient outcome and reduce radiation toxicities.

Biopsy-Guided Pathological Response Assessment in Breast Cancer is Insufficient: Additional Pathology Findings of the MICRA Trial

BACKGROUND

Neoadjuvant systemic treatment (NST) leads to pathologic complete response (pCR) in 10-89% of breast cancer patients depending on subtype. The added value of surgery is uncertain in patients who reach pCR; however, current imaging and biopsy techniques aiming to predict pCR are not accurate enough. This study aims to quantify the residual disease remaining after NST in patients with a favorable response on MRI and residual disease missed with biopsies.

METHODS

In the MICRA trial, patients with a favorable response to NST on MRI underwent ultrasound-guided post-NST 14G biopsies followed by surgery. We analyzed pathology reports of the biopsies and the surgical specimens. Primary outcome was the extent of residual invasive disease among molecular subtypes, and secondary outcome was the extent of missed residual invasive disease.

RESULTS

We included 167 patients. Surgical specimen showed residual invasive disease in 69 (41%) patients. The median size of residual invasive disease was 18 mm (interquartile range [IQR] 12-30) in hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) patients, 8 mm (IQR 3-15) in HR+/HER2-positive (HER2+) patients, 4 mm (IQR 2-9) in HR-negative (HR-)/HER2+ patients, and 5 mm (IQR 2-11) in triple-negative (TN) patients. Residual invasive disease was missed in all subtypes varying from 4 to 7 mm.

CONCLUSION

Although the extent of residual invasive disease is small in TN and HER2+ subtypes, substantial residual invasive disease is left behind in all subtypes with 14G biopsies. This may hamper local control and limits adjuvant systemic treatment options. Therefore, surgical excision remains obligatory until accuracy of imaging and biopsy techniques improve.

Eliminating Breast Surgery for Invasive Cancer with Exceptional Response to Neoadjuvant Systemic Therapy: Prospective Multicenter Clinical Trial Planned Initial Feasibility Endpoint

BACKGROUND

Response to neoadjuvant systemic therapy (NST) for breast cancer enables tailoring of subsequent therapy. Image-guided breast biopsy after NST can accurately predict a pathologic complete response (pCR). The feasibility phase of the clinical trial reported here assesses omission of breast surgery followed by radiotherapy in terms of local recurrence before trial expansion.

STUDY DESIGN

Women with unicentric, cT1-2 N0-1 M0 triple-negative (TNBC) or human epidermal growth factor receptor 2-positive breast cancer (HER2+BC) cancer with <2 cm residual disease on post-NST imaging were eligible to enroll. If no residual invasive or in situ disease was identified by image-guided, vacuum-assisted core biopsy (VACB), breast surgery was omitted, and radiotherapy delivered. The primary endpoint for the feasibility phase was ipsilateral breast tumor recurrence at 6 months. If any recurrence occurred during the feasibility phase the trial would halt.

RESULTS

Thirteen patients were enrolled from March 2017 to October 2018. The mean age was 60.8 years (range 51 to 75) and most patients were White (69.2%) and non-Hispanic/Latino (84.6%). All patients had invasive ductal carcinoma (6 TNBC, 7 HER2+BC). Mean tumor size was 2.4 cm (range 0.9 to 5.0) before NST and 0.7 cm (range 0 to 1.8) after NST. Seven patients (53.8%) had residual disease identified on VACB; the remaining 6 (46.2%) comprised the feasibility cohort. At a median follow-up of 44.3 months (range 41.3 to 51.3) there was no ipsilateral breast tumor recurrence in this cohort.

CONCLUSIONS

These early data suggest that omission of breast surgery in patients with invasive TNBC and HER2+BC with no evidence of residual disease on standardized VACB after NST is potentially feasible. Results from the expansion phase of this clinical trial will be reported per protocol prespecified analyses.

Frequency of axillary nodal complete pathological response of breast cancer patients in neoadjuvant chemotherapy setting: A cross-sectional study

Objectives

Pathological complete response (pCR) occurs in about 20-30% of patients undergoing systemic neoadjuvant therapy. This leads to the idea of sparing the patient the morbidity associated with axillary surgery. "Wait and watch" policy for cancers which achieve complete pathological response on neoadjuvant systemic therapy is a well-established practice in various cancers like the esophagus, rectum and larynx. This has led to organ preservation protocols being practiced worldwide for these cancers without affecting the overall survival of the patient. We believe patients undergoing a complete pathological response in the breast may be spared axillary surgery. Axillary surgery leads to morbidity and extra financial burden with no added advantage in survival.

Material and Methods

A total of 326 patients with breast cancer who had received neoadjuvant systemic chemotherapy from 2015 to 2020 were included in our retrospective study. Final histopathology of the breast and axillary surgery was noted to report the frequency of complete pathological response. The frequency of positive nodal disease with respect to stage, grade and type of cancer was measured.

Results

Among 326 patients, our study showed that 53% of patients with complete pathological response in breast also had complete response in the axilla compared to 43% with incomplete pathological response. No significant difference was found for age, menopausal status, initial tumor size when patients with complete pathological response were compared to non or partial responders. The rate of complete pathological response was higher in patients with clinically node negative patients after NACT, hormone negative, HER2 positive and triple negative population.

Conclusion

Our results indicated that 53% of the patients who developed complete pathological response in the breast underwent needless axillary procedure. Axillary surgery can be staged after the breast surgery if residual tumor is present on the histopathological specimen. In case of pCR, omission of axillary surgery can be considered. However, a larger population, multi-centric studies are needed for treatment guidelines.

Personalizing neoadjuvant immune-checkpoint inhibition in patients with melanoma

Neoadjuvant immune-checkpoint inhibition is a promising emerging treatment approach for patients with surgically resectable macroscopic stage III melanoma. The neoadjuvant setting provides an ideal platform for personalized therapy owing to the very homogeneous nature of the patient population and the opportunity for pathological response assessments within several weeks of starting treatment, thereby facilitating the efficient identification of novel biomarkers. A pathological response to immune-checkpoint inhibitors has been shown to be a strong surrogate marker of both recurrence-free survival and overall survival, enabling timely analyses of the efficacy of novel therapies in patients with early stage disease. Patients with a major pathological response (defined as the presence of ≤10% viable tumour cells) have a very low risk of recurrence, which offers an opportunity to adjust the extent of surgery and any subsequent adjuvant therapy and follow-up monitoring. Conversely, patients who have only a partial pathological response or who do not respond to neoadjuvant therapy still might benefit from therapy escalation and/or class switch during adjuvant therapy. In this Review, we outline the concept of a fully personalized neoadjuvant treatment approach exemplified by the current developments in neoadjuvant therapy for patients with resectable melanoma, which could provide a template for the development of similar approaches for patients with other immune-responsive cancers in the near future.

The nodal positivity rate in breast pCR patients with initially, clinically node-negative breast cancer after neoadjuvant systemic therapy: A systematic review and meta-analysis

Background

The axillary lymph node positive (ypN+) rate in patients with clinically node-negative (cN0) breast cancer who have achieved breast pathologic complete response (bpCR) after neoadjuvant systemic therapy (NST) is extremely low, and this population has the potential to be exempt from sentinel lymph node biopsy (SLNB). However, an overview of the ypN+ rate in this population for different breast cancer subtypes is lacking.

Objective

To provide the pooled ypN+ rate in cN0 patients who achieved bpCR after NST in different breast cancer subtypes defined by hormone receptor (HR) status and human epidermal growth factor receptor 2 (HER2) status.

Methods

A systematic literature search was conducted in Embase and PubMed on July 20, 2022. Two authors independently selected studies that met the inclusion criteria and extracted all data. The pooled ypN+ rates for each subtype were calculated by a random-effects model using the Stata 16.0 metaprop command.

Results

The pooled analysis of 9609 cN0 patients who achieved bpCR showed that the ypN+ rate was lowest for the HR+/HER2+ (0%) subtype, followed by HR+/HER2- (5.1%), HR-/HER2+ (0.6%), and HR-/HER2- (0.3%). Additionally, 6571 cT1-T2N0 patients who achieved bpCR had a pooled ypN+ rate of 0.6%, and the ypN+ rates for different subtypes were as follows: HR+/HER2+ (1.7%), HR+/HER2- (2.7%), HR-/HER2+ (0.1%), and HR-/HER2- (0.8%).

Conclusion

Our results suggested that cN0 patients who achieve bpCR may be exempt from axillary surgery in the HR+/HER2-, HR+/HER2+, and HR-/HER2- subtypes because of the extremely low probability of residual axillary lymph node disease. However, the safety of omitting axillary surgery needs to be further confirmed by prospective studies.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/#recordDetails, identifier CRD42022351739.

De-ESCAlating RadioTherapy in breast cancer patients with pathologic complete response to neoadjuvant systemic therapy: DESCARTES study

PURPOSE

Neoadjuvant systemic therapy (NST) is increasingly used in breast cancer patients and depending on subtype, 10-89% of patients will attain pathologic complete response (pCR). In patients with pCR, risk of local recurrence (LR) after breast conserving therapy is low. Although adjuvant radiotherapy after breast conserving surgery (BCS) reduces LR further in these patients, it may not contribute to overall survival. However, radiotherapy may cause early and late toxicity. The aim of this study is to show that omission of adjuvant radiotherapy in patients with a pCR after NST will result in acceptable low LR rates and good quality of life.

METHODS

The DESCARTES study is a prospective, multicenter, single arm study. Radiotherapy will be omitted in cT1-2N0 patients (all subtypes) who achieve a pCR of the breast and lymph nodes after NST followed by BCS plus sentinel node procedure. A pCR is defined as ypT0N0 (i.e. no residual tumor cells detected). Primary endpoint is the 5-year LR rate, which is expected to be 4% and deemed acceptable if less than 6%. In total, 595 patients are needed to achieve a power of 80% (one-side alpha of 0.05). Secondary outcomes include quality of life, Cancer Worry Scale, disease specific and overall survival. Projected accrual is five years.

CONCLUSION

This study bridges the knowledge gap regarding LR rates when adjuvant radiotherapy is omitted in cT1-2N0 patients achieving pCR after NST. If the results are positive, radiotherapy may be safely omitted in selected breast cancer patients with a pCR after NST.

TRIAL REGISTRATION

This study is registered at ClinicalTrials.gov on June 13th 2022 (NCT05416164). Protocol version 5.1 (15-03-2022).

Surgical Management of the Axilla for Breast Cancer

This review discusses the contemporary surgical management of the axilla in patients with breast cancer. Surgical paradigms are highlighted by clinical nodal status at presentation and treatment approach, including upfront surgery and neoadjuvant systemic therapy settings. This review focuses on the increasing opportunities for de-escalating the extent of axillary surgery in the era of sentinel lymph node biopsy, while also reviewing the remaining indications for axillary clearance with axillary lymph node dissection.

Estimating the Benefit of Preoperative Systemic Therapy to Reduce the Extent of Breast Cancer Surgery: Current Standard and Future Directions

Once reserved for locally advanced tumors which were deemed inoperable at presentation, preoperative systemic therapy (PST) is nowadays increasingly used to treat early breast cancer. PST allows for in vivo assessment of tumor response, for tailoring of adjuvant systemic therapy and for de-escalation of breast and the axillary surgery. Increased rates of pathological complete response together with more accurate response assessment and surgical planning have led to a significant reduction in surgical morbidity. While surgical assessment remains the standard of care, ongoing studies are evaluating whether surgery can be omitted in patients who achieve a complete pathological response. In this chapter, I will review the impact of PST on surgical de-escalation and the data supporting the safety of this approach.

Clearance of ctDNA in triple-negative and HER2-positive breast cancer patients during neoadjuvant treatment is correlated with pathologic complete response

BACKGROUND

Although the standard of care is to perform surgery of primary breast cancer (BC) after neoadjuvant chemotherapy (NAC), for certain patients achieving clinical complete response (cCR) and pathologic complete response (pCR), omission of surgical treatment may be an option. Levels of circulating tumor DNA (ctDNA) during and after therapy could identify patients achieving minimal residual disease. In this study, we evaluated whether ctDNA clearance during NAC could be a correlate to effective response in human epidermal growth factor receptor 2 positive (HER2+) and triple-negative (TN) BC patients.

METHODS

A prospective study was conducted to identify patient-specific PIK3CA and TP53 mutations in tissue using next-generation sequencing, which could then be used to track the presence/absence of mutations prior to, during, and following NAC using Sysmex SafeSEQ technology. All patients underwent a surgical excision after NAC, and pCR was assessed.

RESULTS

A total of 29 TN and HER2+ BC patients were examined and 20 that carried mutations in the PIK3CA and/or TP53 genes were recruited. Overall, 19 of these 20 patients harbored at least one tumor-specific mutation in their plasma at baseline. After NAC, 15 patients (75.0%) achieved pCR according to the histopathologic evaluation of the surgical specimen, and 15 patients (75.0%) had a cCR; 18 of 20 patients (90.0%) had concordant pCR and cCR. The status of 'no mutation detected' (NMD) following NAC in cCR patients correctly identified the pCR in 14 of 15 patients (93.33%), as well as correctly ruled out pCR in three patients, with an accuracy of 89.47%. During the 12-month follow-up after surgery, 40 plasma samples collected from 15 patients all showed no detectable ctDNA (NMD), and no patient recurred.

CONCLUSION

These findings prompt further research of the value of ctDNA for non-invasive prediction of clinical/pathological response, raising the possibility of sparing surgery following NAC in selected BC patients.

Patterns of care over 10 years in young breast cancer patients in the Netherlands, a nationwide population-based study

INTRODUCTION

Each year, around 600 young (<40 years) breast cancer (BC) patients are registered in the national NABON Breast Cancer Audit (NBCA). The aim of this study is to compare patient and treatment characteristics of young and older age BC patients over time with a focus on outcome of quality indicators (QIs). Furthermore, we analysed whether de-escalation trends of treatment can be recognized to the same degree in both patient groups.

MATERIAL AND METHODS

From October 2011 to October 2020 all patients treated for stage I-III invasive BC were included. Tumour characteristics, treatment variables and outcome of QIs of two age categories young (<40 years) and older patient (≥40 years) were analysed.

RESULTS

In total 114,700 patients were included: 4.6% young patients and 95.4% older patients. Young patients more often presented with a palpable mass, higher stage, and triple-negative BC. Overall, young patients more often started with neoadjuvant systemic treatment (NST) (54.3% vs. 18.6%) and a greater proportion of the young patients retained their breast contour after surgery (73.5% vs. 69.3%). De-escalation trends such as decrease in axillary lymph node dissections and in the use of boost were observed. The omission of radiation treatment after breast conserving surgery was only observed in older patients.

CONCLUSION

Although this study shows that young women more often present with unfavourable tumours, therapeutic procedures are performed with a higher adherence to the QIs than for older patients and young women do benefit from some de-escalation trends to the same extend as older patients.

Improving prediction of response to neoadjuvant treatment in patients with breast cancer by combining liquid biopsies with multiparametric MRI: protocol of the LIMA study - a multicentre prospective observational cohort study

INTRODUCTION

The response to neoadjuvant chemotherapy (NAC) in breast cancer has important prognostic implications. Dynamic prediction of tumour regression by NAC may allow for adaption of the treatment plan before completion, or even before the start of treatment. Such predictions may help prevent overtreatment and related toxicity and correct for undertreatment with ineffective regimens. Current imaging methods are not able to fully predict the efficacy of NAC. To successfully improve response prediction, tumour biology and heterogeneity as well as treatment-induced changes have to be considered. In the LIMA study, multiparametric MRI will be combined with liquid biopsies. In addition to conventional clinical and pathological information, these methods may give complementary information at multiple time points during treatment.

AIM

To combine multiparametric MRI and liquid biopsies in patients with breast cancer to predict residual cancer burden (RCB) after NAC, in adjunct to standard clinico-pathological information. Predictions will be made before the start of NAC, approximately halfway during treatment and after completion of NAC.

METHODS

In this multicentre prospective observational study we aim to enrol 100 patients. Multiparametric MRI will be performed prior to NAC, approximately halfway and after completion of NAC. Liquid biopsies will be obtained immediately prior to every cycle of chemotherapy and after completion of NAC. The primary endpoint is RCB in the surgical resection specimen following NAC. Collected data will primarily be analysed using multivariable techniques such as penalised regression techniques.

ETHICS AND DISSEMINATION

Medical Research Ethics Committee Utrecht has approved this study (NL67308.041.19). Informed consent will be obtained from each participant. All data are anonymised before publication. The findings of this study will be submitted to international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04223492.

Factors Associated with Axillary Lymph Node Status in Clinically Node-Negative Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy

Adequate axillary lymph node (ALN) staging is critical for patients with invasive breast cancer. However, neoadjuvant chemotherapy (NAC) was associated with a lower risk of ALN metastasis compared with those who underwent primary surgery among clinically node-negative (cN0) patients. This study aimed to investigate the factors associated with ALN status among patients with cN0 breast cancer undergoing NAC. A total of 222 consecutive patients with cN0 breast cancer undergoing NAC between January 2012 and December 2021 were reviewed. Univariate and multivariate analyses were performed to compare factors associated with positive ALN status. Seventeen patients (7.7%) had ALNs metastases. Here, 90 patients (40.5%) achieved pathologic complete response in the breast (breast-pCR), and all had negative ALN status. Lymphovascular invasion (odds ratio: 29.366, p < 0.0001) was an independent risk predictor of ALN metastasis in all study populations. Among patients without breast-pCR, mastectomies were performed more frequently in patients with ALN metastasis (52.9%) than in those without metastasis (20.9%) (p = 0.013). Our findings support the omission of axillary surgery in patients who achieve breast-pCR. Prospective studies are needed to confirm the feasibility of a future two-stage surgical plan for breast-conserving surgery in patients who are likely to achieve breast-pCR during clinical evaluation.

A review of studies on omitting surgery after neoadjuvant chemotherapy in breast cancer

The advancement in systemic neoadjuvant therapy has significantly increased the pathological complete response (pCR) rate in breast cancer. As surgeries inevitably affect patients physically and psychologically and the accuracy of pCR prediction and diagnosis by minimal invasive biopsy is improving, the necessity of surgery in neoadjuvant chemotherapy (NAC) patients who achieve pCR is under debate. Thus, we conducted a literature review of studies on the selective omission of breast surgery after NAC for breast cancer patients. We summarized the existing predictive models and technologies to predict and diagnose pCR after NAC. Our research indicates that, for nearly half a century, the extent of surgery on both breast and axillary lymph nodes is decreasing, while more precise systematic treatments are increasing. NAC has advanced significantly and its pCR rates have improved, so surgery may be omitted in certain patients. However, accurately predicting pCR after NAC is still a challenge. We also described the design for a randomized clinical trial and the potential problems of omitting surgical treatment after NAC. In summary, the decrease in breast cancer surgery is an unavoidable trend, and more high-quality clinical trials need to be conducted.

Breast Magnetic Resonance Imaging for Patients With Newly Diagnosed Breast Cancer: A Review

Despite the high sensitivity and widespread use of preoperative magnetic resonance imaging (MRI), the American Cancer Society and the National Comprehensive Cancer Network guidelines do not recommend the routine use of preoperative MRI owing to the conflicting results and lack of clear benefit to the surgical outcome (reoperation and mastectomy) and long-term clinical outcomes (local recurrence and metachronous contralateral breast cancer). Preoperative MRI detects additional cancers that are occult at mammography and ultrasound but increases the rate of mastectomy. Concerns about overdiagnosis and overtreatment of preoperative MRI might be mitigated by adjusting the confounding factors when conducting studies, using the state-of-the-art image-guided biopsy technique, applying the radiologists’ cumulative experiences in interpreting MRI findings, and performing multiple lumpectomies in patients with multicentric cancer. Among the various imaging methods, dynamic contrast-enhanced MRI has the highest accuracy in predicting pathologic complete response after neoadjuvant chemotherapy. Prospective trials aimed at applying the MRI information to the de-escalation of surgical or radiation treatments are underway. In this review, current studies on the clinical outcomes of preoperative breast MRI are updated, and circumstances in which MRI may be useful for surgical planning are discussed.

Preoperative Breast Magnetic Resonance Imaging as a Predictor of Response to Neoadjuvant Chemotherapy

Introduction:

The ability to accurately predict pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) in breast cancer would improve patient selection for specific treatment strategies, would provide important information for patients to aid in the treatment selection process, and could potentially avoid the need for more extensive surgery. The diagnostic performance of magnetic resonance imaging (MRI) in predicting pCR has previously been studied, with mixed results. Magnetic resonance imaging performance may also be influenced by tumour and patient factors.

Methods:

Eighty-seven breast cancer patients who underwent NAC were studied. Pre-NAC and post-NAC MRI findings were compared with pathologic findings postsurgical excision. The impact of patient and tumour characteristics on MRI accuracy was evaluated.

Results:

The mean (SD) age of participants was 48.7 (10.3) years. The rate of pCR based on post-NAC MRI was 19.5% overall (19/87). The sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy in predicting pCR were 52.9%, 77.1%, 36.0%, 87.1%, and 72.4%, respectively. Positive predictive value was the highest in nonluminal versus Luminal A disease (45.0% vs 25.0%, P < .001), with higher rates of false positivity in nonluminal subtypes (P = .002). Tumour grade, T category, and histological subtype were all independent predictors of MRI accuracy regarding post-NAC tumour size.

Conclusion:

Magnetic resonance imaging alone is insufficient to accurately predict pCR in breast cancer patients post-NAC. Magnetic resonance imaging predictions of pCR are more accurate in nonluminal subtypes. Tumour grade, T category, and histological subtype should be considered when evaluating post-NAC tumour sizes.

Intelligent Vacuum-Assisted Biopsy to Identify Breast Cancer Patients With Pathologic Complete Response (ypT0 and ypN0) After Neoadjuvant Systemic Treatment for Omission of Breast and Axillary Surgery

PURPOSE

Neoadjuvant systemic treatment (NST) elicits a pathologic complete response in 40%-70% of women with breast cancer. These patients may not need surgery as all local tumor has already been eradicated by NST. However, nonsurgical approaches, including imaging or vacuum-assisted biopsy (VAB), were not able to accurately identify patients without residual cancer in the breast or axilla. We evaluated the feasibility of a machine learning algorithm (intelligent VAB) to identify exceptional responders to NST.

METHODS

We trained, tested, and validated a machine learning algorithm using patient, imaging, tumor, and VAB variables to detect residual cancer after NST (ypT+ or in situ or ypN+) before surgery. We used data from 318 women with cT1-3, cN0 or +, human epidermal growth factor receptor 2-positive, triple-negative, or high-proliferative Luminal B-like breast cancer who underwent VAB before surgery (ClinicalTrials.gov identifier: NCT02948764, RESPONDER trial). We used 10-fold cross-validation to train and test the algorithm, which was then externally validated using data of an independent trial (ClinicalTrials.gov identifier: NCT02575612). We compared findings with the histopathologic evaluation of the surgical specimen. We considered false-negative rate (FNR) and specificity to be the main outcomes.

RESULTS

In the development set (n = 318) and external validation set (n = 45), the intelligent VAB showed an FNR of 0.0%-5.2%, a specificity of 37.5%-40.0%, and an area under the receiver operating characteristic curve of 0.91-0.92 to detect residual cancer (ypT+ or in situ or ypN+) after NST. Spiegelhalter's Z confirmed a well-calibrated model (z score -0.746, P = .228). FNR of the intelligent VAB was lower compared with imaging after NST, VAB alone, or combinations of both.

CONCLUSION

An intelligent VAB algorithm can reliably exclude residual cancer after NST. The omission of breast and axillary surgery for these exceptional responders may be evaluated in future trials.

Breast and axillary surgery after neoadjuvant systemic treatment - A review of clinical routine recommendations and the latest clinical research

Breast and axillary surgery after neoadjuvant systemic treatment for women with breast cancer has undergone multiple paradigm changes within the past years. In this review, we provide a state-of-the-art overview of breast and axillary surgery after neoadjuvant systemic treatment from both, a clinical routine perspective and a clinical research perspective. For axillary disease, axillary lymph node dissection, sentinel lymph node biopsy, or targeted axillary dissection are nowadays recommended depending on the lymph node status before and after neoadjuvant systemic treatment. For the primary tumor in the breast, breast conserving surgery remains the standard of care. The clinical management of exceptional responders to neoadjuvant systemic treatment is a pressing knowledge gap due to the increasing number of patients who achieve a pathologic complete response to neoadjuvant systemic treatment and for whom surgery may have no therapeutic benefit. Current clinical research evaluates whether less invasive procedures can exclude residual cancer after neoadjuvant systemic treatment as reliably as surgery to possibly omit surgery for those patients in the future.

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Breast and axillary surgery after neoadjuvant systemic treatment has evolved.

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Choice of axillary surgery depends on lymph node status before and after treatment.

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Optimal management of exceptional responders to neoadjuvant treatment is unclear.

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Clinical research aims to reliably exclude residual cancer without surgery.

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For exceptional responders, breast cancer surgery may be omitted in the future.

Persistence of ctDNA in Patients with Breast Cancer During Neoadjuvant Treatment Is a Significant Predictor of Poor Tumor Response

PURPOSE

Accurate response assessment during neoadjuvant systemic treatment (NST) poses a clinical challenge. Therefore, a minimally invasive assessment of tumor response based on cell-free circulating tumor DNA (ctDNA) may be beneficial to guide treatment decisions.

EXPERIMENTAL DESIGN

We profiled 93 genes in tissue from 193 patients with early breast cancer. Patient-specific assays were designed for 145 patients to track ctDNA during NST in plasma. ctDNA presence and levels were correlated with complete pathological response (pCR) and residual cancer burden (RCB) as well as clinicopathologic characteristics of the tumor to identify potential proxies for ctDNA release.

RESULTS

At baseline, ctDNA could be detected in 63/145 (43.4%) patients and persisted in 25/63 (39.7%) patients at mid-therapy (MT) and 15/63 (23.8%) patients at the end of treatment. ctDNA detection at MT was significantly associated with higher RCB (OR = 0.062; 95% CI, 0.01-0.48; P = 0.0077). Of 31 patients with detectable ctDNA at MT, 30 patients (96.8%) were nonresponders (RCB II, n = 8; RCB III, n = 22) and only one patient responded to the treatment (RCB I). Considering all 145 patients with baseline (BL) plasma, none of the patients with RCB 0 and only 6.7% of patients with RCB I had ctDNA detectable at MT, whereas 30.6% and 29.6% of patients with RCB II/III, respectively, had a positive ctDNA result.

CONCLUSIONS

Overall, our results demonstrate that the detection and persistence of ctDNA at MT may have the potential to negatively predict response to neoadjuvant treatment and identify patients who will not achieve pCR or be classified with RCB II/III.

De-escalating Surgery Among Patients with HER2 + and Triple Negative Breast Cancer

Purpose of Review

De-escalation of surgery has been central in the evolution of multidisciplinary management of breast cancer. Advances in oncology and increasing use of neoadjuvant chemotherapy (NACT) have opened opportunities for further surgical de-escalation especially for HER2 + and triple negative (TN) disease. The aim of this review is to discuss the recent data on de-escalation of surgery as well as the future directions.

Recent Findings

Patients with TN and HER2 + breast cancer with excellent response to NACT would be the ideal candidates for surgical de-escalation. Post-NACT image-guided biopsy, potentially combined with machine learning algorithms, may accurately identify patients achieving pathologic complete response that would be eligible for clinical trials assessing safety of omission of breast and axillary surgery.

Summary

Multidisciplinary research is required to further support results of preliminary studies. Current data point towards a future when even less or no surgery may be required for exceptional responders.

Pathologic evaluation of specimens after neoadjuvant chemotherapy in breast cancer: Current recommendations and challenges

Neoadjuvant chemotherapy is increasingly used to optimize breast conservation surgery and is becoming a standard of care in a subset of breast cancer patients. An accurate pathologic assessment is crucial in guiding clinical decisions and subsequent management and prognosis. This review aims to summarize the most current literature, recommendations, and challenges in the pathologic evaluation of breast cancer after neoadjuvant chemotherapy. Included are the most current definitions of the different types of tumor response, the underlying factors that can affect tumor response, how to assess lymph nodes, margins, and tumor markers post-neoadjuvant chemotherapy, as well as the different classification systems a pathologist can use to assess residual disease. In this era of de-escalation of surgical treatment, studies on imaging techniques to assess residual disease and avoid surgery after neoadjuvant chemotherapy have also been done. However, at least for now, surgical treatment remains the preferred practice. As such, pathologists play an increasingly critical role in standardizing assessment of residual disease post-neoadjuvant chemotherapy, and in optimizing the knowledge gained by this approach to breast cancer therapy.

Breast cancer-The catalyst of contemporary trials design

Surgical trials in breast cancer have catalyzed contemporary trial design for solid organ cancers and are a prime example of surgeons taking the lead in clinical trial design. Surgeons have lead trials that have improved patient outcomes and quality of life without sacrificing oncologic safety. We have evolved from radical mastectomy to breast conservation and sentinel node biopsy. Contemporary trial design in breast cancer now focus on personalizing care based on tumor genomics.

Innovative Standards in Surgery of the Breast after Neoadjuvant Systemic Therapy

BACKGROUND

The goal of neoadjuvant systemic therapy (NST) in breast cancer is to downstage tumors and downgrade treatment. Indications are constantly evolving. These changes raise practical questions for planning of surgery after NST.

SUMMARY

In this review we discuss current evolving aspects of surgery of the breast after NST. Breast-conserving surgery (BCS) eligibility increases after NST - both neoadjuvant chemotherapy (NAC) and neoadjuvant endocrine therapy. Adequate margin width in NST and upfront surgery are similar - "no tumor on ink" for invasive cancer. Oncoplastic breast surgery after NST is feasible - both for BCS and mastectomy with reconstruction. There is increasing interest in the possibility of omitting surgery in patients with a complete response to NAC. Several trials are being conducted in aim of achieving acceptable prediction of pathological complete response, by combination of imaging and percutaneous biopsy of the tumor bed, as well as assessing the safety of such an approach.

KEY MESSAGES

Surgery of the breast after NST should be determined not only according to biologic and anatomic parameters at diagnosis, but is dynamic, and must be tailored according to the response to therapy. The omission of surgery in exceptional responders after NAC is being explored.

Relationship Between Breast and Axillary Pathologic Complete Response in Women Receiving Neoadjuvant Chemotherapy for Breast Cancer

OBJECTIVE

We aim to delineate the relationship between breast and axillary pathologic complete response (pCR) in patients receiving neoadjuvant chemotherapy for breast cancer.

METHODS

We performed a retrospective cohort study of patients with clinical T1-4N0-3M0 breast cancer receiving neoadjuvant chemotherapy followed by surgical therapy at Sunnybrook Health Sciences Centre in Toronto, Canada between 2014 and 2019. Clinicopathologic data were abstracted from the electronic medical record. Women were stratified into receptor subtypes as follows: hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-), HR+/HER2+, HR-/HER2+ and HR-/HER2- (triple negative) and compared with Fisher's exact test. Our primary outcome was to assess the positive predictive value of breast pCR for determining axillary pCR, and vice versa.

RESULTS

There were 374 breast cancers, with 109 (29.1%) achieving breast pCR (ypT0/Tis). Amongst node-positive tumours achieving breast pCR, rates of associated axillary pCR (ypN0/0i+) were as follows: HR+/HER2- (2/6, 33.3%), HR+/HER2+ (12/13, 92.3%), HR-/HER2+ (15/17, 88.2%) and triple negative (15/17, 88.2%) (P = 0.02). Conversely, amongst node-positive tumours achieving axillary pCR, rates of associated breast pCR were: HR+/HER2- (2/10, 20.0%), HR+/HER2+ (12/23, 52.2%), HR-/HER2+ (15/24, 62.5%) and triple negative (15/26, 57.7%) (P = 0.1).

CONCLUSIONS

Breast pCR is a strong predictor of axillary pCR in women with HER2-positive and triple-negative breast cancers. Conversely, axillary pCR is a modest predictor of breast pCR for these subtypes. There is a poor relationship between breast and axillary pCR in women with hormone receptor-positive disease. These data may inform future de-escalation of surgery in women with HER2-positive and triple-negative disease.

MRI-Based Radiomics Analysis for the Pretreatment Prediction of Pathologic Complete Tumor Response to Neoadjuvant Systemic Therapy in Breast Cancer Patients: A Multicenter Study

This retrospective study investigated the value of pretreatment contrast-enhanced Magnetic Resonance Imaging (MRI)-based radiomics for the prediction of pathologic complete tumor response to neoadjuvant systemic therapy in breast cancer patients. A total of 292 breast cancer patients, with 320 tumors, who were treated with neo-adjuvant systemic therapy and underwent a pretreatment MRI exam were enrolled. As the data were collected in two different hospitals with five different MRI scanners and varying acquisition protocols, three different strategies to split training and validation datasets were used. Radiomics, clinical, and combined models were developed using random forest classifiers in each strategy. The analysis of radiomics features had no added value in predicting pathologic complete tumor response to neoadjuvant systemic therapy in breast cancer patients compared with the clinical models, nor did the combined models perform significantly better than the clinical models. Further, the radiomics features selected for the models and their performance differed with and within the different strategies. Due to previous and current work, we tentatively attribute the lack of improvement in clinical models following the addition of radiomics to the effects of variations in acquisition and reconstruction parameters. The lack of reproducibility data (i.e., test-retest or similar) meant that this effect could not be analyzed. These results indicate the need for reproducibility studies to preselect reproducible features in order to properly assess the potential of radiomics.