Do MRI and mammography reliably identify candidates for breast conservation after neoadjuvant chemotherapy?

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.

Impact of Imaging Biomarkers and AI on Breast Cancer Management: A Brief Review

Breast cancer stands out as the most frequently identified malignancy, ranking as the fifth leading cause of global cancer-related deaths. The American College of Radiology (ACR) introduced the Breast Imaging Reporting and Data System (BI-RADS) as a standard terminology facilitating communication between radiologists and clinicians; however, an update is now imperative to encompass the latest imaging modalities developed subsequent to the 5th edition of BI-RADS. Within this review article, we provide a concise history of BI-RADS, delve into advanced mammography techniques, ultrasonography (US), magnetic resonance imaging (MRI), PET/CT images, and microwave breast imaging, and subsequently furnish comprehensive, updated insights into Molecular Breast Imaging (MBI), diagnostic imaging biomarkers, and the assessment of treatment responses. This endeavor aims to enhance radiologists' proficiency in catering to the personalized needs of breast cancer patients. Lastly, we explore the augmented benefits of artificial intelligence (AI), machine learning (ML), and deep learning (DL) applications in segmenting, detecting, and diagnosing breast cancer, as well as the early prediction of the response of tumors to neoadjuvant chemotherapy (NAC). By assimilating state-of-the-art computer algorithms capable of deciphering intricate imaging data and aiding radiologists in rendering precise and effective diagnoses, AI has profoundly revolutionized the landscape of breast cancer radiology. Its vast potential holds the promise of bolstering radiologists' capabilities and ameliorating patient outcomes in the realm of breast cancer management.

Contrast-enhanced mammography in the assessment of residual disease after neoadjuvant treatment

PURPOSE

To investigate the utility of contrast-enhanced mammography (CEM) as an alternative to breast MRI for the evaluation of residual disease after neoadjuvant treatment (NAT).

METHODS

This prospective study enrolled consecutive women undergoing NAT for breast cancer from July 2017-July 2019. Breast MRI and CEM exams performed after completion of NAT were read independently by two breast radiologists. Residual disease and lesion size on MRI and CEM recombined (RI) and low-energy images (LEI) were compared. Histopathology was considered the reference standard. Statistical analysis was performed using McNemar's and Leisenring's tests. Multiple comparison adjustment was made using Bonferroni procedure. Lesion sizes were correlated using Kendall's tau coefficient.

RESULTS

There were 110 participants with 115 breast cancers. Residual disease (invasive cancer or ductal carcinoma in situ) was detected in 83/115 (72%) lesions on pathology, 71/115 (62%) on MRI, 55/115 (48%) on CEM RI, and 75/115 (65%) on CEM LEI. When using multiple comparison adjustment, no significant differences were detected between MRI combined with CEM LEI and CEM RI combined with CEM LEI, in terms of accuracy (MRI: 77%, CEM: 72%; p ≥ 0.99), sensitivity (MRI: 88%, CEM: 81%; p ≥ 0.99), specificity (MRI: 47%, CEM: 50%; p ≥ 0.99), PPV (MRI: 81%, CEM: 81%; p ≥ 0.99), or NPV (MRI: 60%, CEM: 50%; p ≥ 0.99). Size correlation between pathology and both MRI combined with CEM LEI and CEM RI combined with CEM LEI was moderate: τ = 0. 36 vs 0.33 (p ≥ 0.99).

CONCLUSION

Contrast-enhanced mammography is an acceptable alternative to breast MRI for the detection of residual disease after neoadjuvant treatment.

Multimodality Imaging Review of HER2-positive Breast Cancer and Response to Neoadjuvant Chemotherapy

Human epidermal growth factor receptor 2 (HER2/neu or ErbB2)-positive breast cancers comprise 15%-20% of all breast cancers. The most common manifestation of HER2-positive breast cancer at mammography or US is an irregular mass with spiculated margins that often contains calcifications; at MRI, HER2-positive breast cancer may appear as a mass or as nonmass enhancement. HER2-positive breast cancers are often of intermediate to high nuclear grade at histopathologic analysis, with increased risk of local recurrence and metastases and poorer overall prognosis. However, treatment with targeted monoclonal antibody therapies such as trastuzumab and pertuzumab provides better local-regional control and leads to improved survival outcome. With neoadjuvant treatments, including monoclonal antibodies, taxanes, and anthracyclines, women are now potentially able to undergo breast conservation therapy and sentinel lymph node biopsy versus mastectomy and axillary lymph node dissection. Thus, the radiologist's role in assessing the extent of local-regional disease and response to neoadjuvant treatment at imaging is important to inform surgical planning and adjuvant treatment. However, assessment of treatment response remains difficult, with the potential for different imaging modalities to result in underestimation or overestimation of disease to varying degrees when compared with surgical pathologic analysis. In particular, the presence of calcifications at mammography is especially difficult to correlate with the results of pathologic analysis after chemotherapy. Breast MRI findings remain the best predictor of pathologic response. The authors review the initial manifestations of HER2-positive tumors, the varied responses to neoadjuvant chemotherapy, and the challenges in assessing residual cancer burden through a multimodality imaging review with pathologic correlation. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

State of the Art in 2022 PET/CT in Breast Cancer: A Review

Molecular imaging with positron emission tomography is a powerful and well-established tool in breast cancer management. In this review, we aim to address the current place of the main PET radiopharmaceuticals in breast cancer care and offer perspectives on potential future radiopharmaceutical and technological advancements. A special focus is given to the following: the role of 18F-fluorodeoxyglucose positron emission tomography in the clinical management of breast cancer patients, especially during staging; detection of recurrence and evaluation of treatment response; the role of 16α-18Ffluoro-17β-oestradiol positron emission tomography in oestrogen receptors positive breast cancer; the promising radiopharmaceuticals, such as 89Zr-trastuzumab and 68Ga- or 18F-labeled fibroblast activation protein inhibitor; and the application of artificial intelligence.

Accuracy and Reproducibility of Contrast-Enhanced Mammography in the Assessment of Response to Neoadjuvant Chemotherapy in Breast Cancer Patients with Calcifications in the Tumor Bed

This study aimed to evaluate contrast-enhanced mammography (CEM) accuracy and reproducibility in the detection and measurement of residual tumor after neoadjuvant chemotherapy (NAC) in breast cancer (BC) patients with calcifications, using surgical specimen pathology as the reference. Pre- and post-NAC CEM images of 36 consecutive BC patients receiving NAC in 2012–2020, with calcifications in the tumor bed at diagnosis, were retrospectively reviewed by two radiologists; described were absence/presence and size of residual disease based on contrast enhancement (CE) only and CE plus calcifications. Twenty-eight patients (77.8%) had invasive and 5 (13.9%) in situ-only residual disease at surgical specimen pathology. Considering CE plus calcifications instead of CE only, CEM sensitivity for invasive residual tumor increased from 85.7% (95% CI = 67.3–96%) to 96.4% (95% CI = 81.7–99.9%) and specificity decreased from 5/8 (62.5%; 95% CI = 24.5–91.5%) to 1/8 (14.3%; 95% CI = 0.4–57.9%). For in situ-only residual disease, false negatives decreased from 3 to 0 and false positives increased from 1 to 2. CEM pathology concordance in residual disease measurement increased (R squared from 0.38 to 0.45); inter-reader concordance decreased (R squared from 0.79 to 0.66). Considering CE plus calcifications to evaluate NAC response in BC patients increases sensitivity in detection and accuracy in measurement of residual disease but increases false positives.

Frequency and Outcomes of New Suspicious Lesions on Breast MRI in the Setting of Neoadjuvant Therapy

OBJECTIVE. The purpose of this article was to determine the frequency and outcomes of new suspicious findings on breast MRI after initiation of neoadjuvant therapy. MATERIALS AND METHODS. A retrospective database review identified all breast MRI examinations performed to assess response to neoadjuvant therapy between 2010 and 2018. Cases with new suspicious lesions assessed as BI-RADS 4 or 5 and found after the initiation of neoadjuvant treatment were included. Cases with no pretreatment MRI, cases in which the suspicious lesion was present on the baseline MRI but remained suspicious, and cases with insufficient follow-up were excluded. Radiologic, pathologic, and surgical reports were reviewed. Malignant outcomes were determined by pathologic examination. Benignity was established by pathologic examination, follow-up imaging, or both. A total of 419 breast MRI examinations in 297 women were performed to assess response to neoadjuvant therapy. After exclusions, 23 MRI examinations (5.5%) with new suspicious findings, all assessed as BI-RADS 4, comprised the final cohort. RESULTS. Of the 23 lesions, 13 new suspicious findings (56.5%) were contralateral to the known malignancy, nine (39.1%) were ipsilateral, and one (4.3%) involved the bilateral breasts. Lesion types included mass (16, 69.6%), nonmass enhancement (5, 21.7%) and focus (2, 8.7%). None of the new suspicious findings were malignant. CONCLUSION. New suspicious findings occurred in 5.5% of breast MRI examinations performed to monitor response to neoadjuvant therapy, and none of these new lesions were malignant. Our findings suggest that new lesions that arise in the setting of neoadjuvant therapy are highly unlikely to represent a new site of malignancy, particularly if the index malignancy shows treatment response. Larger studies are needed to confirm whether biopsy may be safely averted in this scenario.

The role of breast MRI in newly diagnosed breast cancer: An evidence-based review

The utility of pre-operative MRI in patients with newly diagnosed invasive breast cancer remains a topic of debate. Those who advocate for pre-treatment imaging contend that MRI may detect additional disease not otherwise appreciated on conventional imaging and may provide more accurate staging information to guide treatment. Additionally, it has been proposed that MRI can be utilized to assess extent of residual disease in patients undergoing neoadjuvant chemotherapy. Conversely, those in opposition maintain that routine pre-operative MRI subjects patients to unnecessary ipsilateral mastectomies and prophylactic contralateral mastectomies with no difference in oncologic outcome. When stratified based on tumor biology and patient characteristics, the data suggests that pre-treatment MRI may be advantageous in certain subsets when compared to the general cohort of breast cancer patients. This review recapitulates the current literature on the impact of breast MRI on the surgical management and outcomes of newly diagnosed breast cancer.

Association of surgical margins with local recurrence in patients undergoing breast-conserving surgery after neoadjuvant chemotherapy

BACKGROUND

The aim of the current study was to report a single-institution experience using breast-conserving surgery after neoadjuvant chemotherapy (NACT), focusing on the association between microscopic resection margin status and locoregional recurrence (LRR).

METHODS

Our institutional prospectively maintained database was reviewed to identify patients who were treated with NACT between January 2008 and April 2018.

RESULTS

Among the main partial mastectomy specimens available for analysis (n = 161), 28 had margins < 1 mm, 21 had margin width of 1-2 mm and the remaining 112 had margins > 2 mm. LRR occurred in 16 patients (9.9%) and distant metastases were detected in 27 (16.8%) patients. There was no significant difference in the LRR between the > 2 mm margin group with a 60-month cumulative survival of 85.2% compared with 76.2% for the ≤2 mm group (P = 0.335) in the Kaplan-Meier analysis. When we stratified patients by margin widths of ≥1 mm or <  1 mm, there was no LRR-free survival benefit observed for the ≥1 mm pathologic excision margin group in the univariate analysis (hazard ratio = 0.443; 95% confidence interval = 0.142-1.383; P = 0.161) with a 60-month cumulative LRR-free survival of 84.9% compared with 69.5% for the < 1 mm margin cohort (P = 0.150).

CONCLUSIONS

In the absence of multiple scattered microscopic tumour foci, a negative margin of no ink on tumour maybe sufficient for stage I-III invasive breast cancer treated with NACT and breast-conserving surgery.

Breast Conservation After Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer: Surgical Results From the BrighTNess Randomized Clinical Trial

Importance

Neoadjuvant systemic therapy (NST) is often administered to enable breast-conserving therapy (BCT) in stages II to III breast cancer.

Objectives

To prospectively evaluate the role of NST in conversion from BCT ineligibility to BCT eligibility and to assess the association of response to NST, germline BRCA (gBRCA) status, and region of treatment with surgical choice in women with triple-negative breast cancer (TNBC).

Design, Setting, and Participants

This prespecified secondary analysis of a multicentered, phase 3, double-blind, randomized clinical trial (BrighTNess) enrolled 634 eligible women across 145 centers in 15 countries in North America, Europe, and Asia. Women with operable, clinical stages II to III TNBC who underwent gBRCA mutation testing before initiating NST were eligible to participate. Data were collected from April 1, 2014, to December 8, 2016. This preplanned analysis was performed from January 5, 2018, to October 28, 2019.

Interventions

Study participants were randomized to receive 12 weeks of weekly paclitaxel alone or with the addition of carboplatin and/or veliparib, followed by 4 cycles of doxorubicin hydrochloride and cyclophosphamide.

Main Outcomes and Measures

Surgeons assessed BCT candidacy by clinical and radiographic criteria before and after NST. Surgical choices and whether BCT eligibility was associated with the likelihood of pathologic complete response were then analyzed.

Results

Among the 634 randomized patients (median age, 51 [range, 22-78] years), pre- and post-NST assessments were available for 604 patients. Of 141 patients deemed BCT ineligible at baseline, 75 (53.2%) converted to BCT eligible. Overall, 342 (68.1%) of 502 patients deemed BCT eligible after NST underwent BCT, including 42 (56.0%) of the 75 who converted to BCT eligible. Patients treated in Europe and Asia were more likely to undergo BCT (odds ratio, 2.66; 95% CI, 1.84-3.84) compared with those treated in North America. Among patients without gBRCA mutation undergoing mastectomy, those treated in North America were more likely to undergo contralateral prophylactic mastectomy (57 of 81 [70.4%] vs 6 of 30 [20.0%]; P < .001). Rates of pathologic complete response were similar between patients deemed BCT eligible at baseline and those who were BCT ineligible but converted to BCT eligibility after NST (55.3 [235 of 425] vs 49.3% [37 of 75]; P = .38).

Conclusions and Relevance

This prospective analysis of NST and BCT eligibility in TNBC demonstrates a conversion from BCT ineligibility to BCT eligibility of 53.2%. Lower BCT rates among eligible patients and higher bilateral mastectomy rates among patients without gBRCA mutation in North America merit investigation.

Trial Registration

ClinicalTrials.gov identifier: NCT02032277.

Complete Breast MRI Response to Neoadjuvant Chemotherapy and Prediction of Pathologic Complete Response

OBJECTIVE

To assess the negative predictive value (NPV) of breast MRI in detecting residual disease after neoadjuvant chemotherapy (NAC) in women with invasive breast cancer, overall and by tumor subtype.

METHODS

An institutional review board approved retrospective study from January 2010 through December 2016 identified patients with invasive breast cancer who achieved complete MRI response to NAC, defined as the absence of residual enhancement in the tumor bed above background parenchymal enhancement. During the study period, it was our routine practice to assign a BI-RADS 1 or 2 assessment to these cases. The NPV was defined as the ability of a complete MRI response to predict pathologic complete response (pCR) at final surgical pathology. Statistical analyses were performed using a Fisher exact test.

RESULTS

Among 244 patients who underwent MRI to assess NAC response, 38 (16%) were determined to have complete MRI response by the interpreting radiologist. Of these, 20/38 (53%) had pCR. Complete MRI response did not significantly predict pCR for the total group (P < 0.9). However, NPVs significantly varied by molecular subtype (P < 0.004). True negative MRIs by tumor subtype were 2/10 (20%) for hormone receptor (HR)+/HER2-, 3/10 (30%) for HR+/HER2+, 6/8 (75%) for HR-/HER+, and 9/10 (90%) for triple negative (TN) subtypes. Complete MRI response significantly predicted pCR for only the TN subtype (NPV 90%; P < 0.02).

CONCLUSIONS

In patients with complete MRI response, 53% had pCR. While MRI lacks sufficient NPV to obviate the need for surgical excision, it may add prognostic value for certain molecular subtypes. The TN subtype demonstrated the highest NPV.

Overview of Breast Cancer Therapy

Breast cancer treatment is multidisciplinary. Most women with early stage breast cancer are candidates for breast-conserving surgery with radiotherapy or mastectomy. The risk of local recurrence and the chance of survival does not differ with these approaches. Sentinel node biopsy is used for axillary staging, and individualized approaches are minimizing the need for axillary dissection in women with positive sentinel nodes. Adjuvant systemic therapy is used in most women based on proven survival benefit, and molecular profiling to individualize treatment based on risk is now a clinical reality for patients with hormone receptor-positive cancers.

Surgical Management of Breast Cancer Treated with Neoadjuvant Therapy

Neoadjuvant therapy (NAT) allows downstaging in some cases of breast cancer. By consequence, it may enable a more conservative surgical approach or make surgery possible in cases ineligible for surgery before NAT. In this article, we review the evidence and management recommendations for optimal surgical treatment in this setting.

Integrating anatomy, radiology, pathology, and surgery: An alternative approach in resecting multifocal and multicentric breast carcinoma

The sick lobe hypothesis provides the basis for a lobar approach in radiology, pathology, and surgical treatment of breast cancer. This approach aims to remove the tumor together with the surrounding field of genetic aberrations. Detailed preoperative lobar imaging that properly maps the disease and assesses its extent guides the parenchymal resection. Integration of our knowledge of breast anatomy and pathology with the results of preoperative radiological mapping is critical in assessing the eligibility of patients with multifocal and/or multicentric breast cancer for breast conservation treatment. Through an appropriately selected incision, a multisegment resection of the diseased lobe(s) is performed, which leaves the residual parenchyma in a formation that allows dovetailing of one part into the other, like the way pieces of a jigsaw puzzle fit together. Detailed pathologic analysis of the surgical specimen provides valuable feedback to the radiologist, establishes the completeness of surgical intervention, and generates predictive information for therapeutic decisions. Our approach is a step in continuous search for ideal tailored therapy to avoid under or over-treatment of breast cancer patients.

Breast magnetic resonance imaging use in patients undergoing neoadjuvant chemotherapy is associated with less mastectomies in large ductal cancers but not in lobular cancers

BACKGROUND

To assess the impact of breast magnetic resonance imaging (MRI) use on surgical outcome per histological breast cancer subtype in patients treated with neoadjuvant chemotherapy.

PATIENTS AND METHODS

All patients aged 18-70 years who underwent neoadjuvant chemotherapy for stage I-III invasive breast cancer in the Netherlands in the years 2011-2013 were identified from the Netherlands Cancer Registry. Patients with cT4 tumours were excluded from the analysis. Use of breast MRI and impact on surgical treatment, resection margins and detection of contralateral breast cancer were analysed by multivariable analyses.

RESULTS

Breast MRI was performed in 2879 (83.9%) out of 3433 patients treated with neoadjuvant chemotherapy. Younger age (odds ratio [OR] 1.42; 95% confidence interval [CI] 1.17-1.71 for 18-50 years compared with 50-70 years), larger tumour stage (OR 1.46 [95% CI 1.15-1.86] for cT3, compared to cT1-2 tumours) and multifocality (OR 1.30; 95% CI 1.04-1.61, versus unifocality) were associated with increased breast MRI use. In ductal breast cancer, after stratification for cT-status, breast MRI use is associated with a significant lower OR for mastectomy as final surgery in cT3 tumours (OR 0.45, 95% CI 0.21-0.99). Resection margin involvement and detection of contralateral breast cancer were not associated with breast MRI use.

CONCLUSION

In patients treated with neoadjuvant chemotherapy, the use of breast MRI was associated with a reduced mastectomy rate, particularly in patients with large invasive ductal breast tumours but not in patients with lobular breast cancer.

Do Calcifications Seen on Mammography After Neoadjuvant Chemotherapy for Breast Cancer Always Need to Be Excised?

BACKGROUND

This study aimed to determine the relationship between mammographic calcifications and magnetic resonance imaging (MRI) tumoral enhancement before and after neoadjuvant chemotherapy (NAC) and to assess the impact of these findings on surgical management.

METHODS

This Institutional Review Board-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study involved breast cancer patients who underwent NAC between 2009 and 2015. The study cohort comprised 90 patients with pre- and posttreatment MRI and mammograms demonstrating calcifications within the tumor bed either at presentation or after treatment. The data gathered included pre- and post-NAC imaging findings and post-NAC histopathology, particularly findings associated with calcifications. Comparisons were made using Fisher's exact test, with p values lower than 0.05 considered significant.

RESULTS

Complete resolution of MRI enhancement occurred for 44% of the patients, and a pathologic complete response (pCR) was achieved for 32% of the patients. No statistically significant correlation between changes in mammographic calcifications and MRI enhancement was found (p = 0.12). Resolution of enhancement was strongly correlated with pCR (p < 0.0001). The majority of the patients with pCR demonstrated complete resolution of enhancement (79%, 23/29). No statistically significant relationship was found between changes in calcifications and rates of pCR (p = 0.06). A pCR was achieved most frequently for patients with resolution of enhancement and new, increasing, or unchanged calcifications (p < 0.0001).

CONCLUSIONS

Although calcifications seen on post-NAC mammography may be associated with benign disease, loss of MRI enhancement does not predict the absence of residual tumor with sufficient accuracy to leave calcifications in place. Complete excision of tumor bed calcifications remains standard practice and a substantial limitation to NAC use for downstaging patients to be eligible for breast conservation treatment.

Performance and Practice Guideline for the Use of Neoadjuvant Systemic Therapy in the Management of Breast Cancer

PURPOSE

The American Society of Breast Surgeons (ASBrS) sought to provide an evidence-based guideline on the use of neoadjuvant systemic therapy (NST) in the management of clinical stage II and III invasive breast cancer.

METHODS

A comprehensive nonsystematic review was performed of selected peer-reviewed literature published since 2000. The Education Committee of the ASBrS convened to develop guideline recommendations.

RESULTS

A performance and practice guideline was prepared to outline the baseline assessment and perioperative management of patients with clinical stage II-III breast cancer under consideration for NST.

RECOMMENDATIONS

Preoperative or NST is emerging as an important initial strategy for the management of invasive breast cancer. From the surgeon's perspective, the primary goal of NST is to increase the resectability of locally advanced breast cancer, increase the feasibility of breast-conserving surgery and sentinel node biopsy, and decrease surgical morbidity. To ensure optimal patient selection and efficient patient care, the guideline recommends: (1) baseline breast and axillary imaging; (2) minimally invasive biopsies of breast and axillary lesions; (3) determination of tumor biomarkers; (4) systemic staging; (5) care coordination, including referrals to medical oncology, radiation oncology, plastic surgery, social work, and genetic counseling, if indicated; (6) initiation of NST; (7) post-NST breast and axillary imaging; and (8) decision for surgery based on extent of disease at presentation, patient choice, clinical response to NST, and genetic testing results, if performed.