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

Incidental breast cancer on CT: factors associated with detection and relationship to prognostics and treatment options

OBJECTIVES

With the increasing use of CT, it may help detecting incidental breast cancers. Our study analysed the relationship between breast cancer detection on CT and features of the cancer, factors related to the scan and report, the treatment offered, and cancer prognostics, in NHS settings.

METHODOLOGY

56 scans in 42 patients were retrospectively included.

RESULTS

38 reports (67.9%) missed the breast cancers. Missed cancers were found to be smaller (P = .0042), progressed more by the time they were diagnosed (P = .0011), and their initial treatment was delayed by a median of 3.4 years (P < .0001). Cancers were more likely to be missed out of hours (P = .0485), in an outpatient reporting session (P = .0397), when the cancer presented as a circumscribed mass (P = .0196), and when the breasts were dense (P = .0250).

CONCLUSION

A significant percentage of breast cancer is missed on CT, with subsequent delay in starting treatment. Systematic approach when reporting, awareness of atypical cancer presentations, and minimizing distractions while reporting, may improve the detection of breast cancer on CT.

ADVANCES IN KNOWLEDGE

This study identified opportunities to detect, and the factors associated with missing and delayed treatment of, incidental breast cancer on CT, specifically in NHS settings. By increasing radiologists' awareness of those factors, it is hoped to prevent delay in treatment of this cohort of cancer patients.

Breast Cancer Surveillance in Patients with a Personal History of Breast Cancer: Updates and Controversies

The increased survival rates for patients with a personal history of breast cancer (PHBC) can be attributed to early detection and advancements in breast cancer treatment. Imaging surveillance is of utmost importance due to the increased risk of local recurrence and the development of new primary breast cancer in patients with PHBC. National and international organizations recommend annual mammography for patients with PHBC; supplemental imaging modalities include contrast-enhanced mammography, whole-breast screening US, and breast MRI. However, the screening protocols and indications for supplemental imaging are significantly heterogeneous. The authors provide a review of current screening guidelines for patients with PHBC to aid understanding of the challenges involved in (a) determining when to initiate or discontinue screening mammography, (b) performing screening versus diagnostic mammography, and (c) performing offline versus live screening. The authors also provide updates on emergent supplemental imaging modalities and compliance with screening recommendations for patients with PHBC. ©RSNA, 2025.

Preoperative breast MRI in HER2-positive/hormone receptor-negative breast cancer: surgical outcomes using propensity score matching

OBJECTIVES

To examine the association between preoperative magnetic resonance imaging (MRI) and surgical outcomes in human epidermal growth factor receptor 2 (HER2)-positive/hormone receptor (HR)-negative breast cancer through a propensity score (PS)-matched analysis.

MATERIALS AND METHODS

Patients with HER2-positive/HR-negative invasive ductal carcinoma between 2007 and 2014 were retrospectively assessed and compared according to whether they underwent preoperative MRI. Inverse probability weighting (IPW) analysis and PS matching were used to adjust 17 covariates to control between the MRI and no-MRI groups. Surgical outcomes were compared between two groups and clinicopathologic variables were evaluated to determine who benefited from MRI.

RESULTS

Among 965 women (mean age ± standard deviation, 52 years ± 10), 423 (44%) underwent preoperative MRI and 542 (56%) did not. In the MRI group, a change in surgical management occurred in 48 patients (11%), and the change was appropriate in 31 of those patients (65%). The MRI group had a lower odds of initial mastectomy (odds ratio [OR], 0.63; 95% confidence interval [CI]: 0.47, 0.84; p = 0.002 and OR, 0.67; 95% CI: 0.48, 0.92; p = 0.01 for IPW and PS matching, respectively) and overall mastectomy (OR, 0.60; 95% [CI]: 0.45, 0.80; p = 0.001 and OR, 0.68; 95% CI: 0.49, 0.93; p = 0.02 for IPW and PS matching, respectively). In the subgroup analysis, asymptomatic patients or those with multifocal or multicentric lesions benefited more from MRI (61% vs 36%, p = 0.006 and 52% vs 31%, p = 0.02, respectively).

CONCLUSION

Patients with HER2-positive/HR-negative breast cancer who received preoperative MRI had a lower likelihood of undergoing mastectomy.

KEY POINTS

Question The role of preoperative MRI in predicting surgical outcomes in patients with HER2-positive/HR-negative breast cancer remains uncertain. Findings Preoperative MRI in HER2-positive/HR-negative breast cancer reduces mastectomy rates without increasing the positive resection margin or reoperation rate. Clinical relevance Preoperative MRI is beneficial in reducing mastectomy rates in women with HER2-positive/HR-negative breast cancer.

Frequency and outcomes of new or suspicious MRI findings on breast MRI for patients on neoadjuvant therapy

PURPOSE

To assess the frequency and outcomes of indeterminate enhancing findings on breast MRI unrelated to the index primary tumor(s) in patients on neoadjuvant therapy (NAT).

MATERIALS AND METHODS

This retrospective review identified all diagnostic breast MRIs performed to evaluate response to NAT at our institution between 2017 and 2020. All exams with indeterminate enhancing findings (BI-RADS 3-5) unrelated to the index tumor(s) for which follow-up imaging or tissue diagnosis was recommended were included. Cases lacking a pre-treatment MRI or those with insufficient follow-up were excluded. Imaging of all post-NAT breast MRIs were re-reviewed. The electronic medical record was reviewed to evaluate patient and lesion characteristics and outcomes.

RESULTS

Between 2017 and 2020, 614/4042 (15.2%) breast MRIs were performed to evaluate response to NAT. After exclusions, 38 of these exams (6.2%) identified 42 indeterminate enhancing findings unrelated to the index tumor for which follow-up imaging (15 exams) or tissue diagnosis (23 exams) was recommended. Fifteen of 42 (35.7%) of the findings were new compared to the pre-treatment baseline MRI, 8/42 (19.0%) increased and 19/42 (45.2%) were present on pre-treatment MRI. Most findings were contralateral to the index tumor (28, 66.7%). Findings were masses (17, 40.4%), focus (15, 35.7%), and non-mass enhancement (10, 23.8%). Of the 42 findings, 19 (45.2%) underwent percutaneous biopsy, 10 (23.8%) underwent surgical biopsy or mastectomy, and 13 (31%) were followed by imaging. Thirty-seven were benign, 4 were high-risk lesions without upgrade (atypical ductal hyperplasia, atypical lobular hyperplasia, and papillomatosis with atypical ductal hyperplasia), and one (2.4%) was malignant (invasive lobular carcinoma), which was non-mass enhancement present on the pre-treatment MRI.

CONCLUSION

Indeterminate enhancing lesions unrelated to the index tumor(s) on breast MRIs performed to assess response to neoadjuvant chemotherapy are uncommon. When present, these lesions have an extremely low likelihood of malignancy, especially when new compared to the pre-treatment MRI.

CLINICAL RELEVANCE

Because incidental indeterminate enhancing lesions on breast MRI at post-NAT follow-up are rarely malignant, radiologists should be judicious in recommending follow-up or tissue diagnosis for such lesions after NAT.

Initial MRI findings predictive of a pathological complete response to neoadjuvant treatments in HER2-positive breast cancers

PURPOSE

This study aimed to determine if initial MRI findings could predict a pathological complete response (pCR) following neoadjuvant systemic therapy (NST) in HER2-positive breast cancers.

METHODS

The study retrospectively included 111 patients (Center 1, training set) and 71 patients (Center 2, validation set) with HER2-positive cancer who underwent NST. Initial clinicopathological data and MRI findings were recorded. Continuous variables were analyzed using the Mann-Whitney and Student's t-tests, while categorical variables were analyzed using the χ2 or Fisher's exact test. Univariate analysis was conducted to determine the associations between these variables and pathological complete response (pCR), defined as the absence of invasive malignant cells in the breast and lymph nodes. Interobserver reproducibility was assessed for associated non-mass enhancement (NME) parameter by analyzing 50 MR studies (intraclass correlation coefficient).

RESULTS

pCR was achieved in 67 patients, 51 (46 %) from Center 1 and 16 (23%) from Center 2 (p = 0.003), with significant differences between Centers 1 and 2 in tumor-infiltrating lymphocyte levels and lymphovascular invasion (p < 0.001). The initial presence of suspicious associated NME was the only significant parameter predictive of pCR (p < 0.001 for Center 1 and 0.04 for Center 2). The inter-observer reproducibility for this MRI feature was good, with an intraclass correlation coefficient of 0.872 (95 % CI: 0.73-1.00).

CONCLUSION

The presence of suspicious associated NME in HER2-positive cancers on the initial MRI study was predictive of achieving pCR after NST. This significant preliminary finding warrants confirmation through prospective multicenter studies.

Deep learning analysis of serial digital breast tomosynthesis images in a prospective cohort of breast cancer patients who received neoadjuvant chemotherapy

PURPOSE

Different imaging tools, including digital breast tomosynthesis (DBT), are frequently used for evaluating tumor response during neoadjuvant chemotherapy (NACT). This study aimed to explore whether using artificial intelligence (AI) for serial DBT acquisitions during NACT for breast cancer can predict pathological complete response (pCR) after completion of NACT.

METHODS

A total of 149 women (mean age 53 years, pCR rate 22 %) with breast cancer treated with NACT at Skane University Hospital, Sweden, between 2014 and 2019, were prospectively included in this observational cohort study (ClinicalTrials.gov: NCT02306096). DBT images from both the cancer and contralateral healthy breasts acquired at three time points: pre-NACT, after two cycles of NACT, and after the completion of six cycles of NACT (pre-surgery) were analyzed. The deep learning AI system used to predict pCR consisted of a backbone 3D ResNet and an attention and prediction module. The GradCAM method was used to obtain insights into the model decision basis through a quantitative analysis of the importance maps on the validation set. Moreover, specific model choices were motivated by ablation studies.

RESULTS

The AI model reached an AUC of 0.83 (95% CI: 0.63-1.00) (test set). The spatial correlation of importance maps for input volumes from the same patient but at different time points was high, possibly indicating that the model focuses on the same areas during decision-making.

CONCLUSIONS

We demonstrate a high discriminative performance of our algorithm for predicting pCR/non-pCR. Availability of larger datasets would permit more comprehensive training of the models and more rigorous evaluation of their prediction performance for future patients.

Radiologic-Pathologic Correlation: Is There an Association Between Contrast-Enhanced Mammography Imaging Features and Molecular Subtypes of Breast Cancer?

OBJECTIVE

This study aims to assess the correlation between imaging features of contrast-enhanced mammography (CEM) and molecular subtypes of breast cancer.

METHODS

This is a retrospective single-institution study of patients who underwent CEM from December 2019 to August 2023. Each patient had at least one histologically proven invasive breast cancer with a core biopsy performed. Patients with a history of breast cancer treatment and lesions not entirely included in the CEM images were excluded. The images were interpreted using the American College of Radiology Breast Imaging Reporting and Data System (ACR BI-RADS) lexicon for CEM, published in 2022. Different imaging features, including the presence of calcifications, architectural distortion, non-mass enhancement, mass morphology, internal enhancement pattern, the extent of enhancement, and lesion conspicuity, were analyzed. The molecular subtypes were studied as dichotomous variables, including luminal A, luminal B, HER2, and basal-like. The association between the imaging features and molecular subtypes was analyzed with a Fisher's exact test. Statistical significance was assumed when the p-value was <0.05.

RESULTS

A total of 31 patients with 36 malignant lesions were included in this study. Sixteen lesions (44.4%) were luminal A, four lesions (11.1%) were luminal B, 10 lesions (27.8%) were HER2, and six (16.7%) were basal-like subtypes. The presence of calcifications was associated with the HER2 subtype (p=0.024). Rim-enhancement on recombined images was associated with a basal-like subtype (p=0.001). Heterogeneous enhancement on recombined images was associated with non-basal-like breast cancer (p=0.027). No statistically significant correlation was found between other analyzed CEM imaging features and molecular subtypes.

CONCLUSION

CEM imaging features, including the presence of calcifications and certain internal enhancement patterns, were correlated with distinguishing breast cancer molecular subtypes and thus may further expand the role of CEM.

High Peritumoral and Intratumoral T2 Signal Intensity in HER2-Positive Breast Cancers on Preneoadjuvant Breast MRI: Assessment of Associations With Histopathologic Characteristics

BACKGROUND. Intratumoral necrosis and peritumoral edema are features of aggressive breast cancer that may present as high T2 signal intensity (T2 SI). Implications of high T2 SI in HER2-positive cancers are unclear. OBJECTIVE. The purpose of this study was to assess associations with histopathologic characteristics of high peritumoral T2 SI and intratumoral T2 SI of HER2-positive breast cancer on MRI performed before initiation of neoadjuvant therapy. METHODS. This retrospective study included 210 patients (age, 24-82 years) with 211 HER2 breast cancers who, from January 1, 2015, to July 30, 2022, underwent breast MRI before receiving neoadjuvant therapy. Two radiologists independently assessed cancers for high peritumoral T2 SI and high intratumoral T2 SI on fat-suppressed T2-weighted imaging and classified patterns of high peritumoral T2 SI (adjacent to tumor vs prepectoral extension). A third radiologist resolved discrepancies. Multivariable logistic regression analyses were performed to identify associations of high peritumoral and intratumoral T2 SI with histopathologic characteristics (associated ductal carcinoma in situ, hormone receptor status, histologic grade, lymphovascular invasion, and axillary lymph node metastasis). RESULTS. Of 211 HER2-positive cancers, 81 (38.4%) had high peritumoral T2 SI, and 95 (45.0%) had high intratumoral T2 SI. A histologic grade of 3 was independently associated with high peritumoral T2 SI (OR = 1.90; p = .04). Otherwise, none of the five assessed histopathologic characteristics were independently associated with high intratumoral T2 SI or high peritumoral T2 SI (p > .05). Cancers with high T2 SI adjacent to the tumor (n = 29) and cancers with high T2 SI with prepectoral extension (n = 52) showed no significant difference in frequency for any of the histopathologic characteristics (p > .05). Sensitivities and specificities for predicting the histopathologic characteristics ranged from 35.6% to 43.7% and from 59.7% to 70.7%, respectively, for high peritumoral T2 SI, and from 37.3% to 49.6% and from 49.3% to 62.7%, respectively, for high intratumoral T2 SI. Interreader agreement was almost perfect for high peritumoral T2 SI (Gwet agreement coefficient [AC] = 0.93), high intratumoral T2 SI (Gwet AC = 0.89), and a pattern of high peritumoral T2 SI (Gwet AC = 0.95). CONCLUSION. The only independent association between histopathologic characteristics and high T2 SI of HER2-positive breast cancer was observed between a histologic grade of 3 and high peritumoral T2 SI. CLINICAL IMPACT. In contrast with previously reported findings in broader breast cancer subtypes, peritumoral and intratumoral T2 SI had overall limited utility as prognostic markers of HER2-positive breast cancer.

PET/CT and SPECT/CT Imaging of HER2-Positive Breast Cancer

HER2 (Human Epidermal Growth Factor Receptor 2)-positive breast cancer is characterized by amplification of the HER2 gene and is associated with more aggressive tumor growth, increased risk of metastasis, and poorer prognosis when compared to other subtypes of breast cancer. HER2 expression is therefore a critical tumor feature that can be used to diagnose and treat breast cancer. Moving forward, advances in HER2 in vivo imaging, involving the use of techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT), may allow for a greater role for HER2 status in guiding the management of breast cancer patients. This will apply both to patients who are HER2-positive and those who have limited-to-minimal immunohistochemical HER2 expression (HER2-low), with imaging ultimately helping clinicians determine the size and location of tumors. Additionally, PET and SPECT could help evaluate effectiveness of HER2-targeted therapies, such as trastuzumab or pertuzumab for HER2-positive cancers, and specially modified antibody drug conjugates (ADC), such as trastuzumab-deruxtecan, for HER2-low variants. This review will explore the current and future role of HER2 imaging in personalizing the care of patients diagnosed with breast cancer.

Recent Developments in Combination Chemotherapy for Colorectal and Breast Cancers with Topoisomerase Inhibitors

DNA topoisomerases are important enzymes that stabilize DNA supercoiling and resolve entanglements. There are two main types of topoisomerases in all cells: type I, which causes single-stranded DNA breaks, and type II, which cuts double-stranded DNA. Topoisomerase activity is particularly increased in rapidly dividing cells, such as cancer cells. Topoisomerase inhibitors have been an effective chemotherapeutic option for the treatment of several cancers. In addition, combination cancer therapy with topoisomerase inhibitors may increase therapeutic efficacy and decrease resistance or side effects. Topoisomerase inhibitors are currently being used worldwide, including in the United States, and clinical trials on the combination of topoisomerase inhibitors with other drugs are currently underway. The primary objective of this review was to comprehensively analyze the current clinical landscape concerning the combined application of irinotecan, an extensively investigated type I topoisomerase inhibitor for colorectal cancer, and doxorubicin, an extensively researched type II topoisomerase inhibitor for breast cancer, while presenting a novel approach for cancer therapy.