The role of digital mammographic surveillance for detection of asymptomatic recurrence in autologous flap reconstructions

OBJECTIVE

To evaluate the utility of digital mammography in detecting asymptomatic malignancy in autologous flap reconstructions after mastectomy.

METHODS

A retrospective database review identified all mammograms performed on asymptomatic patients with flap reconstructions over a 9-year period (1/1/2009 to 12/31/2017). A negative examination was defined as BI-RADS 1 or 2 and a positive examination was defined as BI-RADS 0, 4, or 5 assigned to the mastectomy side. Malignant outcomes were determined by pathology results. Interval cancers, or false negatives, were defined as locoregional malignant diagnosis within one year of a negative mammogram. Sensitivity, specificity, predictive values, abnormal interpretation rate, and cancer detection rate were calculated.

RESULTS

626 mammograms of asymptomatic flap reconstructions were performed in 183 patients. The most common flap type was TRAM (83.5 %, 523/626) and DIEP (13.4 %, 84/626). Most exams (98.2 %, 615/626) were negative, assessed as BI-RADS 1 or 2, with no interval cancers at follow-up. Eleven exams (1.8 %, 11/626) were positive, assessed as BI-RADS 0, 4, or 5. After diagnostic work-up of all BI-RADS 0 exams, 9 cases had a final recommendation for biopsy of which 3 were malignant. Mammography yielded a cancer detection rate of 0.5 % (3/626), abnormal interpretation rate of 1.8 % (11/626), NPV of 100 % (615/615), overall PPV of 27.3 % (3/11), PPV2 (positive predictive value of a biopsy recommendation) of 33.3 % (3/9), sensitivity of 100 % (3/3), and specificity of 98.7 % (615/623).

CONCLUSION

Digital mammography of asymptomatic autologous flap reconstructions after mastectomy demonstrated high sensitivity and low abnormal interpretation rate. Cancer detection rate was comparable to current national benchmarks for mammographic screening in the general U.S. population without mastectomy.

Effect of Longitudinal Variation in Tumor Volume Estimation for MRI-guided Personalization of Breast Cancer Neoadjuvant Treatment

Purpose To investigate the impact of longitudinal variation in functional tumor volume (FTV) underestimation and overestimation in predicting pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC). Materials and Methods Women with breast cancer who were enrolled in the prospective I-SPY 2 TRIAL (Investigation of Serial Studies to Predict Your Therapeutic Response with Imaging and Molecular Analysis 2) from May 2010 to November 2016 were eligible for this retrospective analysis. Participants underwent four MRI examinations during NAC treatment. FTV was calculated based on automated segmentation. Baseline FTV before treatment (FTV0) and the percentage of FTV change at early treatment and inter-regimen time points relative to baseline (∆FTV1 and ∆FTV2, respectively) were classified into high-standard or standard groups based on visual assessment of FTV under- and overestimation. Logistic regression models predicting pCR using single predictors (FTV0, ∆FTV1, and ∆FTV2) and multiple predictors (all three) were developed using bootstrap resampling with out-of-sample data evaluation with the area under the receiver operating characteristic curve (AUC) independently in each group. Results This study included 432 women (mean age, 49.0 years ± 10.6 [SD]). In the FTV0 model, the high-standard and standard groups showed similar AUCs (0.61 vs 0.62). The high-standard group had a higher estimated AUC compared with the standard group in the ∆FTV1 (0.74 vs 0.63), ∆FTV2 (0.79 vs 0.62), and multiple predictor models (0.85 vs 0.64), with a statistically significant difference for the latter two models (P = .03 and P = .01, respectively). Conclusion The findings in this study suggest that longitudinal variation in FTV estimation needs to be considered when using early FTV change as an MRI-based criterion for breast cancer treatment personalization. Keywords: Breast, Cancer, Dynamic Contrast-enhanced, MRI, Tumor Response ClinicalTrials.gov registration no. NCT01042379 Supplemental material is available for this article. © RSNA, 2023 See also the commentary by Ram in this issue.

Abstract P6-01-33: Diffusion-weighted magnetic resonance imaging for subtype-specific prediction of pathologic complete response in neoadjuvant chemotherapy

Background: The apparent diffusion coefficient (ADC) presents a biomarker that is sensitive to tumor cellularity. ADC maps can be calculated from non-contrast diffusion-weighted magnetic resonance imaging (DW-MRI) measurements. ACRIN 6698, a sub-study of clinical trial I-SPY 2, investigated mean ADC – averaged over the whole tumor – as a marker to predict pathologic complete response (pCR) [1]. This work compares a group of histogram-based ADC metrics in addition to mean ADC for early prediction of pCR in patients stratified by breast cancer subtype.

Methods: We performed a retrospective analysis of DW-MRI, dynamic-contrast enhanced (DCE) MRI, and clinical outcome (i.e., pCR at surgery) in a cohort of 79 female patients who were diagnosed with high-risk, stage II/III breast cancer. Patients underwent neoadjuvant chemotherapy (NAC) with paclitaxel (12 weeks), followed by doxorubicin plus cyclophosphamide (12 weeks). The included population represents a subset of the I-SPY 2 cohort and comprises 48 patients with hormone receptor [HR]+/HER2-, and 31 patients with HR-/HER2-. DW- and DCE-MRI acquisitions were performed according to the I-SPY 2 protocol at pretreatment (T0) and after three weeks (T1) and were analyzed to find early treatment percentage (%) change (T0 to T1) in any metric M; where %-change = 100 × (M(T1) – M(T0))/M(T0). Histogram analysis provided nine region-of-interest (ROI)-based ADC metrics (Table 1). ROIs were manually delineated by expert observers in three-dimensional ADC maps, focusing on diffusion-restricted regions [2]. DCE-MRI was analyzed for the integral I-SPY 2 imaging marker of %-change in functional tumor volume (FTV) between T0 and T1. Statistical analysis compared the predictive power of ADC metrics and FTV, including: the receiver-operating-characteristic (ROC) curve from a logistic regression model to predict pCR as ‘positive’, area-under-the-curve (AUC) assessment, and rank-sum Wilcoxon test (p< 0.05: statistically significant).

Results (Table 1): 16 out of 79 (20.3%) patients reached pCR at surgery, with 18.8% pCR among HR+/HER- and 22.6% among HR-/HER2- groups. For all nine computed ADC statistics (listed as median [Q1, Q3], across all patients), %-change was higher in patients who reached pCR than patients with non-pCR (highest value for metric ‘MIN’: 23.9% [-0.9%, 52.5] vs. 16.6% [0.4%, 27.6%], though without statistical significance: p=0.237). Likewise, %-change of FTV was also stronger in pCR patients than non-pCR patients (-58.8% [-80.6%, -22.5%] vs. -28.2% [54.2%, -2.7%], with statistical significance: p=0.036). For all patients combined (n=79), among the various reported ADC metrics, %-change in ‘PCTL_95’ (95th percentile of histogram) yielded the highest AUC (0.7; 95% CI = [0.56, 0.83]; p=0.012). %-change in FTV showed the second highest AUC (0.67; 95% CI = [0.52, 0.82]; p=0.036). By subtype, AUC was highest for %-change of ‘PCTL_95’ (0.69; 95% CI = [0.5, 0.87]; p=0.072) in the HR+/HER2- subgroup; and highest for both %-change of ‘MEAN’ (AUC = 0.73; 95% CI = [0.49, 0.94]; p=0.065) and ‘PCTL_75’ (AUC = 0.73; 95% CI = [0.49, 0.94]; p=0.073) triple negative (HR-/HER2-) subgroup. By comparison, %-change of FTV yielded AUCs of 0.64 (95% CI = [0.41, 0.85]; p=0.191) and 0.71 (95% CI = [0.51, 0.9]; p=0.098) in the HR+/HER2- and triple-negative subgroups, respectively.

Conclusion: Various tumor ADC metrics from non-contrast DW-MRI demonstrate potential biomarkers for assessing responsiveness to NAC at an early treatment timepoint. ADC may have predictive performance that is comparable to FTV, depending on the breast cancer subtype. Observations for %-change in ‘MEAN’ ADC at T1 differed from previous reports [1], which may be explained by the small sample size and single (paclitaxel) drug arm. Additional studies are warranted to include patients of experimental arms and of HER2+ subtypes.

[1] Partridge et al., Radiology 289(3):618-27 (2018)

[2] Nu et al., Tomography 8: 1208-20 (2022)

Results of statistical analysis of ADC-based and FTV markers for predicting treatment response at 3 weeks into NAC. Median [Q1, Q3] values represent the median and interquartile range over the respective patient population regarding the %-change of the respective ADC (FTV) metric from T0 to T1. T0: pretreatment, T1: 3-week timepoint, ADC: apparent diffusion coefficient, MRI: magnetic resonance imaging, DW: diffusion-weighted, DCE: dynamic-contrast enhanced, pCR: pathologic complete response, AUC: area under the ROC curve, 95% CI [LL, UL]: confidence interval lower and upper limit, PCTL_x: xth-percentile of tumor ADC histogram, MEAN: mean of ADC within ROI, MIN: minimum of ADC within ROI, MAX: maximum of ADC within ROI, FTV: functional tumor volume, **: statistically significant.

Citation Format: Judith Zimmermann, Julia Carmona-Bozo, Nu N. Le, Natsuko Onishi, Lisa J. Wilmes, Jessica E. Gibbs, Jiachao Liang, David C. Newitt, Savannah Partridge, Patrick Bolan, Bonnie N. Joe, Elissa R. Price, Barbara LeStage, Nola M. Hylton, Wen Li. Diffusion-weighted magnetic resonance imaging for subtype-specific prediction of pathologic complete response in neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-33.

Diffusion-Weighted MRI for Predicting Pathologic Complete Response in Neoadjuvant Immunotherapy

This study tested the hypothesis that a change in the apparent diffusion coefficient (ADC) measured in diffusion-weighted MRI (DWI) is an independent imaging marker, and ADC performs better than functional tumor volume (FTV) for assessing treatment response in patients with locally advanced breast cancer receiving neoadjuvant immunotherapy. A total of 249 patients were randomized to standard neoadjuvant chemotherapy with pembrolizumab (pembro) or without pembrolizumab (control). DCE-MRI and DWI, performed prior to and 3 weeks after the start of treatment, were analyzed. Percent changes of tumor ADC metrics (mean, 5th to 95th percentiles of ADC histogram) and FTV were evaluated for the prediction of pathologic complete response (pCR) using a logistic regression model. The area under the ROC curve (AUC) estimated for the percent change in mean ADC was higher in the pembro cohort (0.73, 95% confidence interval [CI]: 0.52 to 0.93) than in the control cohort (0.63, 95% CI: 0.43 to 0.83). In the control cohort, the percent change of the 95th percentile ADC achieved the highest AUC, 0.69 (95% CI: 0.52 to 0.85). In the pembro cohort, the percent change of the 25th percentile ADC achieved the highest AUC, 0.75 (95% CI: 0.55 to 0.95). AUCs estimated for percent change of FTV were 0.61 (95% CI: 0.39 to 0.83) and 0.66 (95% CI: 0.47 to 0.85) for the pembro and control cohorts, respectively. Tumor ADC may perform better than FTV to predict pCR at an early treatment time-point during neoadjuvant immunotherapy.

Effect of Inter-Reader Variability on Diffusion-Weighted MRI Apparent Diffusion Coefficient Measurements and Prediction of Pathologic Complete Response for Breast Cancer

This study evaluated the inter-reader agreement of tumor apparent diffusion coefficient (ADC) measurements performed on breast diffusion-weighted imaging (DWI) for assessing treatment response in a multi-center clinical trial of neoadjuvant chemotherapy (NAC) for breast cancer. DWIs from 103 breast cancer patients (mean age: 46 ± 11 years) acquired at baseline and after 3 weeks of treatment were evaluated independently by two readers. Three types of tumor regions of interests (ROIs) were delineated: multiple-slice restricted, single-slice restricted and single-slice tumor ROIs. Compared to tumor ROIs, restricted ROIs were limited to low ADC areas of enhancing tumor only. We found excellent agreement (intraclass correlation coefficient [ICC] ranged from 0.94 to 0.98) for mean ADC. Higher ICCs were observed in multiple-slice restricted ROIs (range: 0.97 to 0.98) than in other two ROI types (both in the range of 0.94 to 0.98). Among the three ROI types, the highest area under the receiver operating characteristic curves (AUCs) were observed for mean ADC of multiple-slice restricted ROIs (0.65, 95% confidence interval [CI]: 0.52–0.79 and 0.67, 95% CI: 0.53–0.81 for Reader 1 and Reader 2, respectively). In conclusion, mean ADC values of multiple-slice restricted ROI showed excellent agreement and similar predictive performance for pathologic complete response between the two readers.

Abstract P3-03-01: Functional tumor volume at 3 and 6-week MRI as an indicator of patients with inferior outcome after neoadjuvant chemotherapy

Purpose. Functional tumor volume (FTV) is a quantitative measure of tumor burden derived from dynamic contrast-enhanced breast MRI1, 2. In the I-SPY 2 TRIAL, FTV is measured during neoadjuvant chemotherapy (NAC) at pre-treatment (T0), 3 weeks (T1), 12 weeks (T2), and pre-surgery (T3) time points. In I-SPY2 protocol amendment 18, activated in Dec 2017, an optional MRI at 6 weeks (T1a) recommended at clinician’s discretion was added for patients with low response at T1. Patients are treated with standard NAC with or without addition of experimental agents. A treatment escalation option being planned for future I-SPY2 implementation will give patients with suboptimal response the opportunity to pursue more aggressive therapy. T1 and T1a MRI may be helpful to select candidates for this option. We retrospectively investigated the ability of FTV reduction at 3 and 6 weeks to detect non-responders. Methods. We included 104 patients who underwent T1a MRI between Jan 2018 and Mar 2021. FTV was measured using in-house software developed in IDL (Exelis Visual Information Solutions, Boulder, CO). FTV reduction at 3 and 6 weeks was dichotomized to under and over with a cutoff of 20% reduction from T0 to T1 and 65% reduction (the 3D equivalent of size-based partial response criteria by RECIST) from T0 to T1a, respectively. Treatment outcome was evaluated based on residual cancer burden (RCB) on surgical pathology, an established surrogate for survival outcome3. Patients with RCB 0/I were considered as responders and those with RCB II/III as non-responders. Fisher’s exact test was used to examine the association between FTV reduction and treatment outcome, with P <0.05 considered statistically significant. Ability of FTV reduction to detect non-responders was assessed by positive predictive value (PPV) and sensitivity, where non-responder was defined as “positive”. Results. Of the 104 patients, 49 patients (31 HR+HER2–;16 HR–HER2–; 2 HR+HER2+) who had both RCB and analyzable FTVs were included. Other patients were excluded because of missing RCB or FTV data (n = 18) or not having completed the assigned therapy (n = 37).FTV reduction at T1 and T1a was associated with outcome (P = 0.022 and <0.001, respectively) (Table 1). FTV reduction at T1a was also associated with outcome in 26 patients with <20% reduction at T1 (P = 0.047). The combined criteria of <20 % reduction at T1 and <65 % reduction at T1a detected non-responders with PPV of 82% and sensitivity of 95%, which outperformed the T1 only or T1a only criterion (Table 2†).Ability of combined criteria was experimentally tested using 20% cutoff for T1 and various cutoffs for T1a (Table 2). Criteria of <20 % reduction at T1 and <50 % reduction at T1a detected non-responders with PPV of 89% and sensitivity of 89%(Table 2‡). Conclusion. In this early small study, combined criteria using FTV reduction at 3 and 6 weeks of NAC showed high PPV and high sensitivity in early detection of non-responders as candidates for the treatment escalation option. Reference. 1. Radiology 263:663–672, 2012. 2. Radiology 279:44–55, 2016. 3. J Clin Oncol. 2007 Oct 01; 25(28) 4414-4422

Table 1.Association between FTV Reduction and Treatment ResponseCriteria based on FTV reduction at T1Total n = 49<20% reduction at T1 (n = 26)>20% reductionat T1 (n = 23)P-valueNon-responder (RCB II or III)281990.022*Responder (RCB 0 or I)21714Criteria based on FTV reduction at T1aTotal n = 49<65% reduction at T1a (n = 30)>65% reduction at T1a (n = 19)P-valueNon-responder (RCB II or III)28244< 0.001*Responder (RCB 0 or I)21615Combined criteria based on FTV reduction at T1 and T1aTotal n = 26<20% reduction at T1 & <65% reduction at T1a (n = 22)<20% reduction at T1 & >65% reduction at T1a (n = 4)P-valueNon-responder (RCB II or III)191810.047*Responder (RCB 0 or I)743

Table 2.Performance of FTV Reduction-based CriteriaCriteria to detect non-respondersPPVNPVSensitivitySpecificityTrue positiveFalse negativeFalse positiveTrue negativeTotalT1 <20% reduction†73%61%68%67%19971449T1a <65% reduction†80%79%86%71%24461549T1 <20% reduction & T1a <40% reduction88%56%79%71%1542526T1 <20% reduction & T1a <45% reduction89%62%84%71%1632526T1 <20% reduction & T1a <50% reduction ‡89%71%89%71%1722526T1 <20% reduction & T1a <55% reduction86%80%95%57%1813426T1 <20% reduction & T1a <60% reduction86%80%95%57%1813426T1 <20% reduction & T1a <65% reduction †82%75%95%43%1814326T1 <20% reduction & T1a <70% reduction78%67%95%29%1815226T1 <20% reduction & T1a <75% decrease75%50%95%14%1816126Note: Unless otherwise specified, data represent the number of patients

Citation Format: Natsuko Onishi, Jessica E Gibbs, Wen Li, David C Newitt, Elissa R Price, Barbara LeStage, William F Symmans, Angela M DeMichele, Christina Yau, the I-SPY 2 TRIAL Imaging Working Group, the I-SPY 2 TRIAL Consortium, Laura J Esserman, Nola M Hylton. Functional tumor volume at 3 and 6-week MRI as an indicator of patients with inferior outcome after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-03-01.

Abstract P3-03-02: Diffusion-weighted MRI for prediction of pathologic complete response in HER2- breast cancer treated with pembrolizumab plus neoadjuvant chemotherapy

Background: Checkpoint blockade pembrolizumab has demonstrated great potential to improve pathologic outcome for HER2- breast cancer. The apparent diffusion coefficient (ADC) is a non-contrast MRI-derived biomarker that is sensitive to changes in tumor cellularity. Clinical trial ACRIN 6698, a sub-study of I-SPY 2, demonstrated that ADC can predict pathologic complete response (pCR). This study compares the utility of ADC for early prediction of pCR in patients with HER2- breast cancer randomized to pembrolizumab versus standard neoadjuvant chemotherapy (NACT) in I-SPY 2. Methods: A retrospective analysis of imaging and clinical data was performed on a cohort of 249 women diagnosed with high-risk, stage II/III breast cancer. All patients were randomized to the standard NACT (paclitaxel) or pembrolizumab plus paclitaxel for 12 weeks, followed by doxorubicin plus cyclophosphamide. MRI exams performed at pretreatment (T0) and 3 weeks after the treatment started (T1) were analyzed. Tumor ADC was calculated within manually delineated region-of-interests on diffusion-weighted MRI. The percent change of ADC from T0 to T1 was evaluated in the prediction of pCR after NACT. Statistical analysis included Wilcoxon rank sum test and the area under the ROC curve (AUC). A p-value <0.05 was considered statistically significant. Results: A subcohort of 103 patients with analyzable diffusion-weighted MRI exams and known pCR (n=30)/non-pCR (n=73) outcome were included in this analysis. Among 103 patients, 62 had HR+/HER2- and 41 had triple negative breast cancer. Twenty-eight patients (17 HR+/HER2- and 11 triple negative) were randomized to receive pembrolizumab and 75 (45 HR+/HER2- and 30 triple negative) to standard NACT. Tumor ADC increased at 3 weeks in both standard and pembrolizumab cohorts with median ADC change of 11.5% (interquartile range [IQR]: 4.6, 16.2)% and 14.4% (IQR: 0.2, 19.9)%, respectively. In the pembrolizumab cohort, the difference in ADC change between non-pCR and pCR groups was estimated as -9.7% (95% confidence interval [CI]: -22.4, -0.9), with ADC increasing more in the pCR group. The AUC of predicting pCR in the pembrolizumab cohort was estimated as 0.73 (95%CI: 0.52, 0.93), while it was estimated as 0.63 (95% CI: 0.43, 0.83) in the standard NACT cohort. In comparison, the AUCs using functional tumor volume (FTV) to predict pCR were 0.61 (95%CI: 0.39, 0.83) and 0.66 (95% CI: 0.47, 0.85) in the corresponding cohorts (Table 1). The results suggest that ADC had higher association with pCR than FTV in the pembrolizumab cohort and FTV had higher association than ADC in the standard cohort. Conclusions: Tumor ADC, measured using diffusion-weighted MRI, demonstrates potential as a biomarker for assessing early response to immunotherapy in the neoadjuvant setting for high risk HER2- breast cancer. This study is limited by sample size. Future analysis with larger cohorts is warranted.

Table 1.Association between MRI variables and pCRN (pCR rate)Difference between non-pCR and pCR groups (95% CI)AUC (95% CI)pDiffusion weighted MRI (percent change of ADC)Pembrolizumab28 (54%)-9.7 (-22.4, -0.9)0.73 (0.52, 0.93)0.041Standard75 (20%)-5.6 (-13.9, 2.1)0.63 (0.43, 0.83)0.13DCE-MRI (percent change of FTV)Pembrolizumab28 (54%)10.6 (-18.3, 43.9)0.61 (0.39, 0.83)0.34Standard74 (20%)25.3 (-0.6, 49)0.66 (0.47, 0.85)0.056

Citation Format: Wen Li, Nu N Le, Natsuko Onishi, David C Newitt, Jessica E Gibbs, Lisa J Wilmes, John Kornak, Savannah C Partridge, Barbara LeStage, Elissa R Price, Bonnie N Joe, I-SPY 2 TRIAL Imaging Working Group, I-SPY 2 TRIAL Consortium, Laura J Esserman, Nola M Hylton. Diffusion-weighted MRI for prediction of pathologic complete response in HER2- breast cancer treated with pembrolizumab plus neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-03-02.

Abstract P3-03-08: Background parenchymal enhancement as an imaging biomarker in neoadjuvant endocrine therapy for DCIS

Purpose. Hormonal status significantly affects background normal parenchymal enhancement (BPE) degree on breast MRI. A previous study reported the association between lack of BPE suppression and non pathologic complete response (pCR) after neoadjuvant chemotherapy for HR+ invasive cancer1. For DCIS, local control is the treatment goal2,3. Surgical outcomes which might be related to local control include presence of invasive components at surgery, re-excision after breast conserving surgery (BCS), and residual DCIS extent. We hypothesized that imaging outcomes (pre-surgery MRI volume and volume reduction from baseline) might also be related to local control. We investigated the association between BPE degree/suppression and 5 surgical/imaging outcomes after neoadjuvant endocrine therapy (NET) for DCIS. Methods. CALGB 40903 was a single arm trial of NET for ER+ DCIS without invasion4. Clinical and image data from a subset of 59 post-menopausal patients from this trial was available for analysis. Patients took letrozole 2.5 mg/day for 6 months before surgery (BCS, 53; mastectomy, 6). Dynamic contrast-enhanced MRIs were obtained at baseline, 3 months, and 6 months (pre-surgery). MRI volume was measured by summing all voxels with pre-defined level of enhancement within a 3D bounding box. MRI volume reduction was measured by percent change from baseline. BPE degree was calculated as the mean early percent enhancement of the central 50% axial slices on a contralateral breast. BPE suppression was dichotomized as suppressed or non-suppressed relative to baseline. For analyses on re-excision, only BCS patients were included. For analyses on residual DCIS extent, patients who achieved pCR or had invasive components were excluded. Mann-Whitney, Spearman’s rho, and Fisher’s exact tests were used for analyses, with P <0.05 considered statistically significant. Results. Of the 59 patients, 9 patients achieved pCR and 50 patients had residual DCIS (6 had invasive components). 8 patients had re-excision. Tables 1 and 2 show results for BPE degree and BPE suppression, respectively. Mean BPE degree at baseline, 3 and 6 months was significantly higher for patients who had re-excision than those who did not (P = 0.019, 0.018, and 0.009, respectively). BPE degree at 6 months showed a moderate positive correlation with pre-surgery MRI volume and volume reduction (rho = 0.42 and 0.50, respectively). Patients with non-suppressed BPE at 6 months had significantly larger MRI volume (P = 0.015) and less MRI volume reduction (P = 0.001) than those with suppressed BPE. No association was found between BPE and presence of invasive components and residual DCIS extent. Conclusion. In this experimental study, lack of BPE suppression was associated with larger MRI volume and less volume reduction after NET. Higher BPE degree was associated with re-excision after BCS. BPE should be further developed as an imaging biomarker for response to NET in DCIS. Reference. 1. Cancer Research, 80(4 Suppl), 2020: 2019 SABCS Abstract PD9-05. 2. J Clin Oncol 31:4054-59, 2013. 3. Cancer. 124(7) 1335-41, 2018. 4. J Clin Oncol. 38(12) 1284-92, 2020

Table 1.Association of BPE Degree with Surgical and Imaging OutcomesOutcomeTime pointOutcome statusNo. of patientsMedian [1st, 3rd quartiles]P-valuePresence of invasive componentBaselineAbsent47 (92)25.0 [19.6, 30.0]0.282Present4 (8)17.2 [15.3, 25.5]3 monthsAbsent48 (91)23.5 [17.8, 31.0]0.668Present5 (9)16.6 [16.3, 34.7]6 monthsAbsent45 (90)24.6 [18.1, 33.0]0.343Present5 (10)17.2 [12.8, 31.2]OutcomeTime pointOutcome statusNo. of patientsMedian [1st, 3rd quartiles]P-valueRe-excision after BCSBaselineNot performed40 (87)22.6 [19.0, 27.1]0.019*Performed6 (13)43.0 [29.3, 53.9]3 monthsNot performed40 (85)22.1 [16.5, 29.5]0.018*Performed7 (15)36.7 [29.2, 40.3]6 monthsNot performed37 (84)19.8 [16.5, 31.4]0.009*Performed7 (16)38.3 [31.4, 41.0]OutcomeTime pointOutcome statusNo. of patientsSpearman’s rhoP-valueResidual DCIS extentBaselineNA3800.9973 monthsNA38-0.270.1016 monthsNA37-0.230.164MRI volumeBaselineNA510.130.3733 monthsNA530.170.2326 monthsNA500.420.003*MRI volume reductionBaselineNA510.070.6093 monthsNA530.290.0336 monthsNA500.50< 0.001** P <0.05; BCS = breast conserving surgery; Data in parentheses are percentages.

Table 2.Association of BPE suppression with Surgical and Imaging OutcomesOutcomeTime pointBPE suppression groupNo. of patientsNo. of patients w/o invasive componentNo. of patients w/invasive componentP-valuePresence of invasive component3 monthssuppressed26 (53)24 (53)2 (50)1.000non-suppressed23 (47)21 (47)2 (50)6 monthssuppressed25 (53)22 (51)3 (75)0.611non-suppressed22 (47)21 (49)1 (25)OutcomeTime pointBPE suppression groupNo. of patientsNo. of patients w/o re-excisionNo. of patients w/re-excisionP-valueRe-excision after BCS3 monthssuppressed26 (53)22 (51)4 (67)0.671non-suppressed23 (47)21 (49)2 (33)6 monthssuppressed25 (53)21 (51)4 (67)0.670non-suppressed22 (47)20 (49)2 (33)OutcomeTime pointBPE suppression groupNo. of patientsMedian[1st, 3rd quartiles]P-valueResidual DCIS extent3 monthssuppressed19 (53)23mm[7, 36]0.172non-suppressed17 (47)11mm[4, 22]6 monthssuppressed18 (51)20mm[6.5, 34]0.487non-suppressed17 (49)18mm[4, 24]MRI volume3 monthssuppressed26 (53)0.4cc[0.2, 1.9]0.613non-suppressed23 (47)0.6cc[0.1, 1.6]6 monthssuppressed25 (53)0.3cc[0.1, 0.8]0.015*non-suppressed22 (47)1.1cc[0.4, 2.8]MRI volume reduction3 monthssuppressed26 (53)-73.0%[-91.4, -45.0]0.684non-suppressed23 (47)-71.1%[-92.1, -46.7]6 monthssuppressed25 (53)-84.8%[-96.2, -66.5]0.001*non-suppressed22 (47)-48.6%[-75.0, 57.3]* P <0.05; BCS = breast conserving surgery; Data in parentheses are percentages.

Citation Format: Natsuko Onishi, David C Newitt, Jessica E Gibbs, Alex A Nguyen, Rita Freimanis, Elissa R Price, Shelly Hwang, Nola M Hylton. Background parenchymal enhancement as an imaging biomarker in neoadjuvant endocrine therapy for DCIS [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-03-08.

Breast MRI during Neoadjuvant Chemotherapy: Lack of Background Parenchymal Enhancement Suppression and Inferior Treatment Response

Background Suppression of background parenchymal enhancement (BPE) is commonly observed after neoadjuvant chemotherapy (NAC) at contrast-enhanced breast MRI. It was hypothesized that nonsuppressed BPE may be associated with inferior response to NAC. Purpose To investigate the relationship between lack of BPE suppression and pathologic response. Materials and Methods A retrospective review was performed for women with menopausal status data who were treated for breast cancer by one of 10 drug arms (standard NAC with or without experimental agents) between May 2010 and November 2016 in the Investigation of Serial Studies to Predict Your Therapeutic Response with Imaging and Molecular Analysis 2, or I-SPY 2 TRIAL (NCT01042379). Patients underwent MRI at four points: before treatment (T0), early treatment (T1), interregimen (T2), and before surgery (T3). BPE was quantitatively measured by using automated fibroglandular tissue segmentation. To test the hypothesis effectively, a subset of examinations with BPE with high-quality segmentation was selected. BPE change from T0 was defined as suppressed or nonsuppressed for each point. The Fisher exact test and the Z tests of proportions with Yates continuity correction were used to examine the relationship between BPE suppression and pathologic complete response (pCR) in hormone receptor (HR)-positive and HR-negative cohorts. Results A total of 3528 MRI scans from 882 patients (mean age, 48 years ± 10 [standard deviation]) were reviewed and the subset of patients with high-quality BPE segmentation was determined (T1, 433 patients; T2, 396 patients; T3, 380 patients). In the HR-positive cohort, an association between lack of BPE suppression and lower pCR rate was detected at T2 (nonsuppressed vs suppressed, 11.8% [six of 51] vs 28.9% [50 of 173]; difference, 17.1% [95% CI: 4.7, 29.5]; P = .02) and T3 (nonsuppressed vs suppressed, 5.3% [two of 38] vs 27.4% [48 of 175]; difference, 22.2% [95% CI: 10.9, 33.5]; P = .003). In the HR-negative cohort, patients with nonsuppressed BPE had lower estimated pCR rate at all points, but the P values for the association were all greater than .05. Conclusions In hormone receptor-positive breast cancer, lack of background parenchymal enhancement suppression may indicate inferior treatment response. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Philpotts in this issue.

Abstract PS3-02: Radiologic review to refine selection of candidates for de-escalation of neoadjuvant therapy

PurposeIn the on-going I-SPY2 TRIAL, participants receive 12 cycles of weekly paclitaxel with or without addition of experimental agents for 12 weeks (first regimen), followed by 4 cycles of anthracycline-cyclophosphamide (AC, second regimen) prior to surgery. A de-escalation strategy currently being introduced in I-SPY2 will give patients the option to skip AC if it is highly likely that they have achieved early pathologic complete response (pCR) at the inter-regimen time point (12 weeks). To guide selection of candidates for this option, a prediction model combining subtype-specific MRI predictive probabilities with mid-treatment percutaneous core biopsy pathology has been developed. The combined model predicts a patient as early pCR if the MRI model based on a quantitative measure of functional tumor volume predicts a high likelihood of pCR, and pathology determines that there are no invasive cancer cells detected in the mid-treatment core biopsy. This study was performed to develop radiologic criteria for post-selection review to further reduce the possibility for incorrect de-escalation recommendation.

MethodsA review of 87 I-SPY2 patients with serial MRI and inter-regimen core biopsy identified 25 patients where both the subtype specific MRI model and at least 2 of 11 I-SPY2 pathologists predicted early pCR. One radiologist retrospectively reviewed MRIs at pre-treatment and inter-regimen for the 25 patients in a blinded fashion, and labeled the presence of residual disease on MRI at inter-regimen as follows: rank 0, no residual disease; rank 1, possible residual disease; rank 2, obvious residual disease.To evaluate the accuracy of selecting candidates for de-escalation of neoadjuvant therapy (i.e. predicting patients with early pCR at inter-regimen), surgical pathology of pCR after the completion of NAC (both first and second regimens) was defined as a surrogate “truth” in this study. Positive predictive value (PPV) and sensitivity for the combined MRI-pathology model were computed for all pathologist pairs. After adding qualitative radiologic review, patients labeled as rank 2 were excluded from the candidates with predicted early pCR by the combined MRI-pathology model. PPV and sensitivity before and after radiologic review were compared.

ResultsThe 25 patients included 21 patients that ultimately achieved pCR, and 4 patients that did not. Radiologic review of the inter-regimen MRI for these patients classified their MRIs as 20% (5/25) rank 0 (no residual disease), 36% (9/25) rank 1 (possible residual disease), and 44% (11/25) rank 2 (obvious residual disease). Most (3/4) non-pCR patients were classified rank 2, however one (1/4) was assessed rank 0. Eight of the 21 pCR patients (38%) were classified as having obvious residual disease on inter-regimen MRI. Without radiologic review, the combined MRI-pathology model predicted pCR with a mean PPV of 92% (range 83-100%) and a mean sensitivity of 91% (range 76-100%). When patients labeled as rank 2 by radiologic review were excluded from candidates with predicted early pCR, PPV increased to 99% (range 93-100%) at the expense of lower sensitivity of 59% (range 52-62%).

Conclusion

In this study, elimination of rank 2 lesions resulted in substantial improvement in PPV (92% to 99%) with a consequent reduction in sensitivity from 91% to 59%. Notably, none of the rank 1 lesions, where diagnostic interpretation was less certain, were found to be non-pCR at surgery. High PPV is essential to ensure high accuracy and safety in directing early pCR patients to therapy de-escalation. These findings will be further validated in continuing studies and radiologic re-review will be included in the de-escalation strategy for omission of AC in the I-SPY2 TRIAL.

Citation Format: Natsuko Onishi, Wen Li, Sara J Venters, Denise M Wolf, David C Newitt, Elissa R Price, Jessica Gibbs, Barbara LeStage, the I-SPY 2 Pathology Working Group, the I-SPY 2 Imaging Working Group, the I-SPY 2 Consortium, William F Symmans, Nola M Hylton. Radiologic review to refine selection of candidates for de-escalation of neoadjuvant therapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS3-02.

Post-lumpectomy breast calcifications: Can original tumor features assist in determining need for biopsy?

OBJECTIVE

The objective of our study was to determine whether, in the digital era, imaging features of a primary breast tumor can be used to influence the decision to biopsy ipsilateral breast calcifications that occur following surgery in women treated with breast conservation surgery (BCS).

MATERIALS AND METHODS

We retrospectively identified women treated with BCS who subsequently developed suspicious calcifications in the treated breast (BI-RADS 4 or 5) from January 2012 - December 2018. Only cases with histopathological diagnosis by stereotactic or surgical biopsy were included. Pathology reports were reviewed, and biopsy results were considered malignant if invasive carcinoma or ductal carcinoma in situ (DCIS) was found. All other results were considered benign. Fisher's exact test was done comparing frequencies of malignancy between those patients whose original tumor had calcifications versus those whose original tumors were not calcified.

RESULTS

Of 90 women with suspicious calcifications on a post-BCS mammogram, 65 (72.2%) were biopsy proven benign and 25 (27.8%) were malignant. The original tumor presented without calcifications in 39 patients (43%), and 51 (57%) had calcifications with or without associated mass, focal asymmetry, or architectural distortion. New calcifications were less likely to be malignant if the original tumor presented without calcifications (5/39; 12.8%) as compared to original tumors with calcifications (20/51; 38.5%) [p-value < 0.05].

CONCLUSION

New calcifications after BCS are significantly less likely to be malignant if the original tumor presented without calcifications. However, with a PPV of 12.8%, even calcifications in a patient with a non-calcified primary tumor require biopsy.

Intermediary clip placement to assist accurate axillary lymph node localization

Localization of metastatic axillary lymph nodes in breast cancer patients is an increasingly common procedure performed by radiologists. In 2014, the National Comprehensive Cancer Network guidelines stated that "clinically positive axillary lymph node (s) should be sampled by FNA or core biopsy and clipped with image-detectable marker; clipped lymph nodes must be removed if FNA or core biopsy was positive prior to neoadjuvant therapy". Since then, multiple studies have further supported targeted axillary surgery after neoadjuvant chemotherapy (NAC), with excision of the clipped metastatic axillary node in addition to the sentinel node (s). Requests for image guided localization of clipped axillary nodes will continue to increase and likely become the standard of care. However, when lymph nodes have decreased in size after NAC, or when small deep lymph nodes are sampled, the clipped node can be difficult to identify under ultrasound at the time of localization. When the target node is questionable, we have found it valuable to place an intermediary clip, and use an axillary mammographic view to confirm this intermediary clip co-localizes with the intended target. With this confirmation, safe, accurate localization can then be performed. We describe 3 cases of intermediary clip placement facilitating successful localization of previously clipped axillary lymph nodes.

Predicting breast cancer response to neoadjuvant treatment using multi-feature MRI: results from the I-SPY 2 TRIAL

Dynamic contrast-enhanced (DCE) MRI provides both morphological and functional information regarding breast tumor response to neoadjuvant chemotherapy (NAC). The purpose of this retrospective study is to test if prediction models combining multiple MRI features outperform models with single features. Four features were quantitatively calculated in each MRI exam: functional tumor volume, longest diameter, sphericity, and contralateral background parenchymal enhancement. Logistic regression analysis was used to study the relationship between MRI variables and pathologic complete response (pCR). Predictive performance was estimated using the area under the receiver operating characteristic curve (AUC). The full cohort was stratified by hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status (positive or negative). A total of 384 patients (median age: 49 y/o) were included. Results showed analysis with combined features achieved higher AUCs than analysis with any feature alone. AUCs estimated for the combined versus highest AUCs among single features were 0.81 (95% confidence interval [CI]: 0.76, 0.86) versus 0.79 (95% CI: 0.73, 0.85) in the full cohort, 0.83 (95% CI: 0.77, 0.92) versus 0.73 (95% CI: 0.61, 0.84) in HR-positive/HER2-negative, 0.88 (95% CI: 0.79, 0.97) versus 0.78 (95% CI: 0.63, 0.89) in HR-positive/HER2-positive, 0.83 (95% CI not available) versus 0.75 (95% CI: 0.46, 0.81) in HR-negative/HER2-positive, and 0.82 (95% CI: 0.74, 0.91) versus 0.75 (95% CI: 0.64, 0.83) in triple negatives. Multi-feature MRI analysis improved pCR prediction over analysis of any individual feature that we examined. Additionally, the improvements in prediction were more notable when analysis was conducted according to cancer subtype.

Superparamagnetic Iron Oxide Sentinel Node Tracer Injection: Effects on Breast MRI Quality

OBJECTIVE

To evaluate the MRI artifact rendered by the typical injection of a ferromagnetic tracer now being intermittently used for intraoperative sentinel node (SN) identification at our institution, and to explore its impact on postoperative imaging and management.

METHODS

This study was Institutional Review Board-approved and granted a waiver of consent. A database search tool was used to identify MRI exams performed on patients who had previously undergone breast-conserving surgery with use of a superparamagnetic iron oxide (SPIO) SN tracer between January 1, 2015, and May 1, 2020. MRI reports, images, and relevant demographic, oncologic, and surgical history were collected. The presence or absence of SPIO residue on breast MRI, as well as its impact on image quality, were extracted from the prospective reports.

RESULTS

A total of 21 MRI exams were identified in 16 patients who had undergone breast-conservation therapy for cancer with use of SPIO SN tracer. Mean time from particle injection to baseline postoperative MRI exam was 10.8 months. All reports (21/21) noted evidence of SPIO residue. Of these, 5/21 were assessed as non-diagnostic; the remainder were assessed as limited.

CONCLUSION

Radiologists should be aware of the use of superparamagnetic tracers for SN identification and the impact on the quality of future MRI examinations. Alternative injection approaches are being developed and sequence parameters adjusted to minimize artifact.

Primum non nocere: Utility and outcomes of pediatric breast ultrasound

PURPOSE

To assess the use and outcomes of ultrasound for the evaluation of breast signs and symptoms in pediatric females.

METHODS

A retrospective database review identified all patients ≤18-years-old who underwent breast ultrasound at an academic institution over a 20-year period. Each symptomatic site was designated a case and analyses were performed on each case. Imaging findings were obtained from the radiology reports. Clinical and pathology data were obtained from the medical records. Descriptive statistics were performed.

RESULTS

The final cohort comprised 124 cases in 101 patients. Mean age was 15 years (range 1-18). The most common indication for ultrasound was a palpable lump (71%). Thirty-seven cases (30%) demonstrated no sonographic correlate to the symptom; 36 (29%) had a benign correlate. The most common benign correlates were abscess/phlegmon and cyst. All cases of abscess/phlegmon had infectious symptoms. Fifty-one cases (41%) demonstrated a sonographic mass that was not characteristically benign. Of these indeterminate masses, 27 were recommended for biopsy, 13 for short-interval follow-up, and 6 had no recommendation. Of 27 biopsied masses, 63% were fibroadenomas. No symptoms were due to malignancy. Therefore, the NPV of ultrasound was 100% and the PPV 0%.

CONCLUSION

In this cohort of pediatric and adolescent patients, malignancy was never the cause of breast symptoms. Imaging yielded false positives with a biopsy recommendation in 22% of cases. Ultrasound provided value in evaluating infectious symptoms. Given the extreme rarity of breast cancer in this population, surveillance may be a safe alternative for most indeterminate lesions.

Utilization of Patient Navigators in Breast Imaging Facilities Across the United States: A Survey of Breast Imaging Radiologists

OBJECTIVE

To assess the utilization of patient navigators at breast imaging facilities across the United States.

METHODS

An online survey was distributed to physician members of the Society of Breast Imaging. Questions encompassed use of patient navigators in breast imaging including: presence and qualifications, roles in patient care, perceived benefits, and barriers. Data were analyzed to identify the overall prevalence of patient navigators, their responsibilities and qualifications, and the impact on breast imaging centers.

RESULTS

Three-hundred and eighty-five board-certified radiologists practicing in the United States completed the survey. The most common practice types were private practice (52%; 201/385) and academic (29%; 110/385). The majority (67%; 256/385) employed navigators, and the most common qualification was a registered nurse (78%; 200/256). Navigators were used for a variety of patient communication and care coordination roles, most commonly to provide educational resources (86%; 219/256), assist patients with scheduling appointments (80%; 205/256), explain the biopsy process (76%;195/256), and communicate biopsy results (64%). Nearly all (99%; 254/256) respondents ranked patient navigators as valuable to extremely valuable in improving patient care and indicated they would recommend implementation of a patient navigation program to other breast imaging practices. The most common barrier to employing a navigator was the financial cost.

CONCLUSION

Patient navigators have been widely adopted in breast imaging practices across the United States, with two-thirds of respondents reporting use of a navigator. Although navigator roles varied by practice, nearly all radiologists utilizing patient navigators found that they positively impact patient care and would recommend them to other breast imaging practices.

Abstract P2-14-01: The impact of local therapy on locoregional recurrence in women with high risk breast cancer in the neoadjuvant I-SPY2 TRIAL

Background: In women with breast cancer receiving neoadjuvant chemotherapy, residual cancer burden (RCB) predicts distant recurrence and survival. In those with high risk tumors, locoregional recurrence (LRR) remains a concern, and has been associated with type of local therapy received. We evaluated the impact of local therapy on LRR in the ISPY-2 TRIAL.

Methods: Data were analyzed in Stata 14.2, using Chi2 test, log rank test, and a Cox proportional hazards model. RCB was considered a categorical variable (0/1 versus 2/3), as described in prior publications. Breast surgery categories were lumpectomy +/- radiotherapy, or mastectomy +/- radiotherapy. Axillary surgery was defined as sentinel lymph node (SLN) surgery (≤6 nodes removed) or axillary dissection (&gt;6 nodes).

Results: Follow up data from the I-SPY2 TRIAL were available for 630 patients (median follow up 2.76 yrs, range 0.4-7.2). Type of local therapy was significantly associated with clinical stage at presentation, with stage III patients most frequently undergoing mastectomy + radiation (p&lt;0.001). Women with higher RCB were more likely to undergo mastectomy than those with lower RCB (61.3% vs 48.8% mastectomy rate, p=0.002), and more likely to receive adjuvant radiotherapy (62.0% vs 53.9%, p=0.048). There was no association between clinical stage, type of surgery, or radiotherapy and LRR (Table). Higher RCB was significantly associated with LRR, with 3 year locoregional recurrence free rate of 95.1% in RCB 0/1 versus 89.9% in RCB 2/3 (p=0.003).

In a Cox model adjusting for clinical stage, tumor subtype, surgical therapy, RCB status, nodal radiation, and age, significant predictors for LRR were tumor subtype and RCB status. Hazard ratio (HR) for LRR in those with RCB 0/1 was 0.39 compared to those with RCB 2/3 (95% CI 0.17-0.87, p=0.021). There was no difference in LRR between breast conservation and mastectomy; within the breast conservation group, those who had lumpectomy alone had higher hazard of LRR compared to those having lumpectomy + radiation (HR 3.1, 95% CI 1.1-9.2, p=0.043).

Conclusions: Extent of surgical therapy was not associated with local tumor control, regardless of advanced tumor stage at presentation. Rather, tumor biology and response to therapy were the best predictors of LRR. These data highlight the opportunity to minimize the morbidity of extensive surgical therapy for patients with excellent response to systemic therapy.

LRR rates by clinical features and treatment status FrequencyLRR RateP valueClinical Stage  0.5I240 (47.5%)5.8% II185 (36.6%)8.7% III80 (15.8%)6.3% Tumor Subtype  0.014ER+PR+Her2-161 (26.4%)3.1% ER+PR-Her2-56 (9.2%)3.6% Her2+176 (28.9%)6.3% Triple negative216 (35.5%)11.1% Local therapy  0.169Lumpectomy85 (13.5%)11.8% Lumpectomy with radiation198 (31.4%)5.6% Mastectomy173 (27.5%)5.2% Mastectomy with radiation174 (27.6%)8.6% Axillary surgery  0.23None5 (0.8%)20% SLN329 (52.2%)5.8% ALND296 (47%)8.5% Axillary radiation  0.535Yes42 (6.7%)9.5% No588 (93.3%)7.0% Axillary management  0.2No surgery or radiation5 (0.8%)20.0% SLN312 (50%)5.3% SLN+Axillary radiation17 (2.7%)8.3% ALND271 (43%)10.3% ALND+Axillary radiation25 (4%)5.4% RCB  0.0020/1293 (50.1%)3.8% 2/3292 (49.9%)10.3% 

Citation Format: Silverstein J, Suleiman L, Yau C, Price ER, Singhrao R, Yee D, DeMichele A, Isaacs C, Albain KS, Chien AJ, Forero-Torres A, Wallace AM, Pusztai L, Ellis ED, Elias AD, Lang JE, Lu J, Han HS, Clark AS, Korde L, Nanda R, Northfelt DW, Khan QJ, Viscusi RK, Euhus DM, Edmiston KK, Chui SY, Kemmer K, Wood WC, Park JW, Liu MC, Olopade O, Leyland-Jones B, Tripathy D, Moulder SL, Rugo HS, Schwab R, Lo S, Helsten T, Beckwith H, I-SPY 2 TRIAL Consortium, Berry DA, Asare SM, Esserman LJ, Boughey JC, Mukhtar RA. The impact of local therapy on locoregional recurrence in women with high risk breast cancer in the neoadjuvant I-SPY2 TRIAL [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-01.

Exploration of PET and MRI radiomic features for decoding breast cancer phenotypes and prognosis

Radiomics is an emerging technology for imaging biomarker discovery and disease-specific personalized treatment management. This paper aims to determine the benefit of using multi-modality radiomics data from PET and MR images in the characterization breast cancer phenotype and prognosis. Eighty-four features were extracted from PET and MR images of 113 breast cancer patients. Unsupervised clustering based on PET and MRI radiomic features created three subgroups. These derived subgroups were statistically significantly associated with tumor grade (p = 2.0 × 10⁻⁶), tumor overall stage (p = 0.037), breast cancer subtypes (p = 0.0085), and disease recurrence status (p = 0.0053). The PET-derived first-order statistics and gray level co-occurrence matrix (GLCM) textural features were discriminative of breast cancer tumor grade, which was confirmed by the results of L2-regularization logistic regression (with repeated nested cross-validation) with an estimated area under the receiver operating characteristic curve (AUC) of 0.76 (95% confidence interval (CI) = [0.62, 0.83]). The results of ElasticNet logistic regression indicated that PET and MR radiomics distinguished recurrence-free survival, with a mean AUC of 0.75 (95% CI = [0.62, 0.88]) and 0.68 (95% CI = [0.58, 0.81]) for 1 and 2 years, respectively. The MRI-derived GLCM inverse difference moment normalized (IDMN) and the PET-derived GLCM cluster prominence were among the key features in the predictive models for recurrence-free survival. In conclusion, radiomic features from PET and MR images could be helpful in deciphering breast cancer phenotypes and may have potential as imaging biomarkers for prediction of breast cancer recurrence-free survival.

Automated analyses of breast scans taken with two types of medical imaging technologies can help oncologists decode clinically relevant features, a finding that could help personalize cancer diagnosis and treatment. Youngho Seo from the University of California, San Francisco, USA, and coworkers extracted 84 quantitative features from positron emission tomography and magnetic resonance imaging scans performed on 113 women with breast cancer. The researchers then applied data-characterization and pattern-recognition algorithms—which included machine-learning methods and engineered features coded by experts—to create classification models that helped uncover disease characteristics that were not obvious to the naked eye. These models successfully subdivided patients according to tumor grade, overall stage, cancer subtype and disease recurrence risk, providing proof of principle that radiomic analyses of this kind could provide valuable information for personalized management of breast cancer.

Qualitative Radiogenomics: Association between Oncotype DX Test Recurrence Score and BI-RADS Mammographic and Breast MR Imaging Features

Purpose To evaluate the association between Breast Imaging Reporting and Data System (BI-RADS) mammographic and magnetic resonance (MR) imaging features and breast cancer recurrence risk in patients with estrogen receptor-positive breast cancer who underwent the Oncotype DX assay. Materials and Methods In this institutional review board-approved and HIPAA-compliant protocol, 408 patients diagnosed with invasive breast cancer between 2004 and 2013 who underwent the Oncotype DX assay were identified. Mammographic and MR imaging features were retrospectively collected according to the BI-RADS lexicon. Linear regression assessed the association between imaging features and Oncotype DX test recurrence score (ODxRS), and post hoc pairwise comparisons assessed ODxRS means by using imaging features. Results Mammographic breast density was inversely associated with ODxRS (P ≤ .05). Average ODxRS for density category A was 24.4 and that for density category D was 16.5 (P < .02). Both indistinct mass margins and fine linear branching calcifications at mammography were significantly associated with higher ODxRS (P < .01 and P < .03, respectively). Masses with indistinct margins had an average ODxRS of 31.3, which significantly differed from the ODxRS of 18.5 for all other mass margins (P < .01). The average ODxRS for fine linear branching calcifications was 29.6, whereas the ODxRS for all other suspicious calcification morphologies was 19.4 (P < .03). Average ODxRS was significantly higher for irregular mass margins at MR imaging compared with spiculated mass margins (24.0 vs 17.6; P < .02). The presence of nonmass enhancement at MR imaging was associated with lower ODxRS than was its absence (16.4 vs 19.9; P < .05). Conclusion The BI-RADS features of mammographic breast density, calcification morphology, mass margins at mammography and MR imaging, and nonmass enhancement at MR imaging have the potential to serve as imaging biomarkers of breast cancer recurrence risk. Further prospective studies involving larger patient cohorts are needed to validate these preliminary findings. ^© RSNA, 2017 Online supplemental material is available for this article.

Use of the probably benign (BI-RADS category 3) assessment for masses on breast MRI: Is it transferable to general clinical practice?

The purpose of this study was to identify potential BI-RADS 3 mass descriptors on breast magnetic resonance imaging by systematically defining positive predictive values (PPV). In a blinded retrospective review of BI-RADS 4 masses, reader 1 identified 132 masses and reader 2 identified 76 masses. PPV for mass descriptors and for descriptor combinations was determined. No mass descriptor resulted in a PPV ≤2% (BI-RADS 3 threshold). Descriptors with the lowest PPVs were circumscribed margin (8%), rim internal enhancement and persistent kinetics (13% each), and oval shape (15%). The results demonstrate the difficulty in transferring the theoretical concept of lesion surveillance to systematic clinical use.

Breast MR imaging for the assessment of residual disease following initial surgery for breast cancer with positive margins

OBJECTIVES

To determine the accuracy of post-operative MR in predicting residual disease in women with positive margins, emphasizing the size thresholds at which residual disease can be confidently identified.

METHODS

This IRB-approved HIPAA-compliant retrospective study included 175 patients with MR after positive margins following initial surgery for breast cancer. Two expert readers independently re-evaluated MR images for evidence of residual disease at the surgical cavity and multifocal/multicentric disease. All patients underwent definitive surgery and MR findings were correlated to histopathology.

RESULTS

139/175 (79.4%) patients had residual disease at surgery. Average overall sensitivity, specificity, PPV and NPV for residual disease at the surgical cavity were 73%, 72%, 91% and 45%, respectively. The readers identified 42/45 (93%, reader 1) and 43/45 (95%, reader 2) patients with residual invasive disease at the cavity of ≥5 mm and 22/22 (100%, both readers) patients with disease ≥10 mm. Average sensitivity, specificity, PPV and NPV for unknown multifocal/multicentric disease were 90%, 96%, 93% and 86%, respectively.

CONCLUSIONS

Post-operative breast MR can accurately depict ≥5-mm residual disease at the surgical cavity and unsuspected multifocal/multicentric disease. These findings have the potential to lead to more appropriate selection of second surgical procedures in women with positive margins.

KEY POINTS

• Post-operative breast MRI accurately defines residual disease of ≥5 mm. • Surgical cavity sensitivities were high for both invasive carcinoma and DCIS. • Post-surgical changes and very small residual disease (<5 mm) may overlap. • Post-operative breast MRI may help planning an accurate re-resection.

MRI-guided breast interventions

Magnetic resonance imaging (MRI)-guided interventions, including biopsies and wire localizations, are fundamental to any breast imaging practice due to the high sensitivity but limited specificity of breast MRI. The basic steps of MRI-guided biopsies are similar regardless of the vendor or platform, and technical considerations include approach planning, patient preparation and positioning, lesion targeting, and directional sampling using a vacuum-assisted biopsy technique. Unique challenges related to MRI-guided biopsies include vanishing lesions due to contrast washout, obscuration of the biopsy site due to susceptibility artifacts, and limited access to posteromedial lesions. A careful approach to planning, patient positioning, and lesion targeting will maximize the chances for a successful biopsy. Due to overlapping imaging features between benign and malignant lesions, radiologic-pathologic concordance is difficult and essential for further patient management.

LEVEL OF EVIDENCE

5 Technical Efficacy: Stage 3 J. MAGN. RESON. IMAGING 2017;46:631-645.

How to use magnetic resonance imaging following neoadjuvant chemotherapy in locally advanced breast cancer

Magnetic resonance imaging (MRI) is highly sensitive in identifying residual breast cancer following neoadjuvant chemotherapy (NAC), and consequently is a commonly used imaging modality in locally advanced breast cancer patients. In these patients, tumor response is an important prognostic indicator. However, discrepancies between MRI findings and surgical pathology are well documented. Overestimation of residual disease by MRI may result in greater surgery than is actually required while underestimation may result in insufficient surgery. Thus, it is important to understand when MRI findings are reliable and when they are less accurate. MRI most accurately predicts pathology in triple negative, Her2 positive and hormone receptor negative tumors, especially if they are of a solid imaging phenotype. In these cases, post-NAC MRI is highly reliable for surgical planning. Hormone receptor positive cancers and those demonstrating non mass enhancement show lower concordance with surgical pathology, making surgical guidance more nebulous in these cases. Radiologists and surgeons must assess MRI response to NAC in the context of tumor subtype. Indiscriminate interpretations will prevent MRI from achieving its maximum potential in the pre-operative setting.

Abstract P3-01-04: Mammographic changes after oncoplastic reduction mammoplasty

BACKGROUND:

Reconstruction of partial lumpectomy defects with reduction mammaplasty techniques can improve aesthetic outcomes. However, the impact of the significant tissue rearrangement on post-operative mammographic findings and subsequent recommendations for biopsy has not been well-studied.

METHODS:

A retrospective review of 50 patients who underwent partial mastectomy with immediate oncoplastic reduction mammaplasty reconstruction from 2001 to 2008 was performed. Mammography reports at 6 months, 1 year, 2 years, and 3 years post-operatively were reviewed for Breast Imaging Reporting and Data System (BI-RADS) scores, predominant findings, and recommendations for subsequent imaging or biopsy.

RESULTS:

At six months post-operatively, 49 patients (98%) had benign findings of post-surgical changes, while one patient had microcalcifications and underwent subsequent surgical re-excision with residual DCIS on pathologic analysis. At one year, 94% of patients continued to have benign mammograms; of these mammograms, 94% reported only post-surgical scarring, while 6% described benign-appearing scattered or dystrophic calcifications. Of the three patients with suspicious mammograms at one year, all underwent core biopsies with benign results. At two years, rates of fat necrosis (2%) and scattered or dystrophic calcifications (10%) increased, though all mammographic findings were considered benign and none required additional imaging or biopsies. By three years post-operatively, an additional two patients (4%) developed suspicious findings and underwent biopsies confirming local recurrence (one invasive, one in situ). The remaining 96% continued to have benign mammographic findings and were subsequently followed with routine biannual mammographic surveillance.

Overall, 88% of patients required no additional intervention in the three-year period following oncoplastic reduction mammaplasty. Of patients recommended for biopsy, malignancy was discovered in 50%, including two local recurrences (4% of total patients). This data is similar to a previously published large study (1841 women) of mammographic surveillance after partial mastectomy without oncoplastic reconstruction at our institution, which found a 6% malignancy rate at 5 years.

CONCLUSIONS:

Although substantial tissue rearrangement is performed at the time of oncoplastic reduction mammaplasty, our results demonstrate low rates of abnormal post-operative mammograms and subsequent biopsies over the first three years following the procedure. These findings support the use of oncoplastic reduction mammaplasty as a strategy for improving reconstructive outcomes in patients undergoing partial mastectomy.

Citation Format: Anne Warren Peled, Merisa Piper, Laura J Esserman, Robert D Foster, Hani Sbitany, Elissa R Price. Mammographic changes after oncoplastic reduction mammoplasty [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-01-04.

Extra-mammary findings on breast MRI: a pictorial review

Recent improvements in breast coil performance have made detection of extra-mammary findings increasingly common. Some of these findings have important clinical implications. The radiologist should be aware of the spectrum of extra-mammary pathologies found on breast magnetic resonance imaging (MRI) and be able to distinguish clinically significant findings from those that are inconsequential. The purpose of this essay is to demonstrate various common and uncommon extra-mammary findings encountered while interpreting breast MRI and to detail appropriate management recommendations.

The California breast density information group: a collaborative response to the issues of breast density, breast cancer risk, and breast density notification legislation

In anticipation of breast density notification legislation in the state of California, which would require notification of women with heterogeneously and extremely dense breast tissue, a working group of breast imagers and breast cancer risk specialists was formed to provide a common response framework. The California Breast Density Information Group identified key elements and implications of the law, researching scientific evidence needed to develop a robust response. In particular, issues of risk associated with dense breast tissue, masking of cancers by dense tissue on mammograms, and the efficacy, benefits, and harms of supplementary screening tests were studied and consensus reached. National guidelines and peer-reviewed published literature were used to recommend that women with dense breast tissue at screening mammography follow supplemental screening guidelines based on breast cancer risk assessment. The goal of developing educational materials for referring clinicians and patients was reached with the construction of an easily accessible Web site that contains information about breast density, breast cancer risk assessment, and supplementary imaging. This multi-institutional, multidisciplinary approach may be useful for organizations to frame responses as similar legislation is passed across the United States. Online supplemental material is available for this article.

c-Kit triggers dual phosphorylations, which couple activation and degradation of the essential melanocyte factor Mi

Microphthalmia (Mi) is a bHLHZip transcription factor that is essential for melanocyte development and postnatal function. It is thought to regulate both differentiated features of melanocytes such as pigmentation as well as proliferation/survival, based on phenotypes of mutant mouse alleles. Mi activity is controlled by at least two signaling pathways. Melanocyte-stimulating hormone (MSH) promotes transcription of the Mi gene through cAMP elevation, resulting in sustained Mi up-regulation over many hours. c-Kit signaling up-regulates Mi function through MAP kinase phosphorylation of Mi, thereby recruiting the p300 transcriptional coactivator. The current study reveals that c-Kit signaling triggers two phosphorylation events on Mi, which up-regulate transactivation potential yet simultaneously target Mi for ubiquitin-dependent proteolysis. The specific activation/degradation signals derive from MAPK/ERK targeting of serine 73, whereas serine 409 serves as a substrate for p90 Rsk-1. An unphosphorylatable double mutant at these two residues is at once profoundly stable and transcriptionally inert. These c-Kit-induced phosphorylations couple transactivation to proteasome-mediated degradation. c-Kit signaling thus triggers short-lived Mi activation and net Mi degradation, in contrast to the profoundly increased Mi expression after MSH signaling, potentially explaining the functional diversity of this transcription factor in regulating proliferation, survival, and differentiation in melanocytes.

Isolation of mouse stromal cells associated with a human tumor using differential diphtheria toxin sensitivity

Tumor vascularization is accompanied by the migration of stromal cells, including endothelial cells, smooth muscle cells, and fibroblasts, into the tumor. The biological contributions of stromal cells to tumor vascularization have not been well-defined, partly due to the difficulty of culturing stromal cells in the presence of large numbers of fast-growing tumor cells. To address this problem, a strategy was devised to kill tumor cells but not stromal cells. Advantage was taken of the observation that diphtheria toxin (DT) kills human but not rodent cells. Human melanoma (MMAN) tumor cells were injected subcutaneously into nude mice. The tumors were excised, homogenized, and treated with 50 ng/ml DT for 24 hours. Elimination of melanoma cells by DT treatment was demonstrated by lack of detectable levels of microphthalmia, a transcription factor that is a marker for melanoma cells. The murine stromal cells were viable and found to be mostly smooth muscle cells. These cells constituted about 1.5% of the MMAN tumor. RNase protection assays using a specific murine vascular endothelial growth factor probe confirmed the murine origin of the stromal cells. This method allows rapid isolation of stromal cells and should facilitate biochemical and genetic analysis of tumor-stromal interactions.

alpha-Melanocyte-stimulating hormone signaling regulates expression of microphthalmia, a gene deficient in Waardenburg syndrome

The pituitary peptide alpha-melanocyte-stimulating hormone (alpha-MSH) stimulates melanocytes to up-regulate cAMP, but the downstream targets of cAMP are not well understood mechanistically. One consequence of alpha-MSH stimulation is increased melanization attributable to induction of pigmentation enzymes, including tyrosinase, which catalyzes a rate-limiting step in melanin synthesis. The tyrosinase promoter is a principle target of the melanocyte transcription factor Microphthalmia (Mi), a factor for which deficiency in humans causes Waardenburg syndrome II. We show here that both alpha-MSH and forskolin, a drug that increases cAMP, stimulate a rapid increase in Mi mRNA and protein levels in both melanoma cell lines and primary melanocytes. This up-regulation requires a cAMP-responsive element within the Mi promoter, and the pathway leading to Mi stimulation is subject to tight homeostatic regulation. Although cAMP signaling is ubiquitous, the Mi promoter was seen to be cAMP-responsive in melanocytes but not in nonmelanocytes. Moreover, dominant negative interference with Mi impeded successful alpha-MSH stimulation of tyrosinase. The regulation of Mi expression via alpha-MSH thus provides a direct mechanistic link to pigmentation. In addition, because the human melanocyte and deafness condition Waardenburg syndrome is sometimes caused by haploinsufficiency of Mi, its modulation by alpha-MSH suggests therapeutic strategies targeted at up-regulating the remaining wild type Mi allele.

Lineage-specific signaling in melanocytes. C-kit stimulation recruits p300/CBP to microphthalmia

During melanocyte development, the cytokine Steel factor activates its receptor c-Kit, initiating a signal transduction cascade, which is vital for lineage determination via unknown downstream nuclear targets. c-Kit has recently been found to trigger mitogen-activated protein kinase-mediated phosphorylation of Microphthalmia (Mi), a lineage-restricted transcription factor, which, like Steel factor and c-Kit, is essential for melanocyte development. This cascade results in increased Mi-dependent transcriptional reporter activity. Here we examine the mechanism by which Mi is activated by this pathway. Phosphorylation does not significantly alter Mi's nuclear localization, DNA binding, or dimerization. However, the transcriptional coactivator p300/CBP selectively associates with mitogen-activated protein kinase-phosphorylated Mi, even under conditions in which non-MAPK phospho-Mi is more abundant. Moreover, p300/CBP coactivates Mi transcriptional activity in a manner dependent upon this phosphorylation. Mi thus joins CREB as a transcription factor whose signal-responsive phosphorylation regulates coactivator recruitment, in this case modulating lineage development in melanocytes.

MAP kinase links the transcription factor Microphthalmia to c-Kit signalling in melanocytes

Germline mutations at loci encoding the transcription factor Microphthalmia (Mi), the cytokine receptor c-Kit, or its ligand Steel factor (S1) result in strikingly similar defects in mast cell and melanocyte development. Here we describe a biochemical link between Kit signalling and the activity of Mi. Stimulation of melanoma cells with S1 results in activation of MAP kinase, which in turn phosphorylates Mi at a consensus target serine. This phosphorylation upregulates Mi transactivation of the tyrosinase pigmentation gene promoter. In addition to modulating pigment production, such signalling may regulate the expression of genes essential for melanocyte survival and development. The pathway represents a new application of the general MAP kinase machinery in transducing a signal between a tissue-specific receptor at the cell surface and a tissue-specific transcription factor in the nucleus.

Role of kinases and the phosphatase calcineurin in the nuclear shuttling of transcription factor NF-AT4

A new facet of calcium signalling involves the nuclear import of the NF-AT transcription factors from their dormant position in the cytoplasm. The protein phosphatase calcineurin appears to play an essential role in activating NF-AT nuclear import, as the calcineurin inhibitors cyclosporin A and FK506 block dephosphorylation and nuclear import of NF-AT (refs 4-7). Here we show that calcium signalling induces an association between NF-AT4 and calcineurin, and that these molecules are transported, as a complex, to the nucleus, where calcineurin continues to dephosphorylate NF-AT4. We propose that a nuclear complex of NF-AT4 and calcineurin maintains calcium signalling by counteracting a vigorous nuclear NF-AT kinase.

The latch region of calcineurin B is involved in both immunosuppressant-immunophilin complex docking and phosphatase activation

The immunosuppressants cyclosporin A and FK506, when complexed with their intracellular receptors, prevent T cell activation by directly binding to the phosphatase calcineurin. We have used molecular modeling and mutagenesis to identify sites on calcineurin important for this interaction. We have created calcineurins that are resistant to both cyclosporin A and FK506 by mutating specific residues in CnB, a calcium-binding protein that regulates the catalytic subunit, CnA. Significantly, on a model of CnB, these mutations map to the latch region, an element of tertiary structure that forms when CnB binds CnA. In addition, we show that this latch region plays an important role in activating the catalytic subunit CnA. These results suggest a molecular mechanism for suppression of calcineurin by cyclosporin A and FK506 involving their binding to the same region of CnB used for allosterically activating CnA.

Cyclophilin B trafficking through the secretory pathway is altered by binding of cyclosporin A

Cyclophilin B is targeted to the secretory pathway via an endoplasmic reticulum signal sequence. We analyzed the localization and trafficking of endogenous and transfected cyclophilin B in mammalian cells. Cyclophilin B accumulates both in the endoplasmic reticulum and in complexes on the plasma membrane. The immunosuppressant cyclosporin A specifically mobilizes cyclophilin B from the endoplasmic reticulum, and promotes the secretion of cyclophilin B into the medium. We suggest that cyclosporin A competes with endogenous plasma membrane proteins for association with cyclophilin B in the secretory pathway. These findings argue in favor of a role for cyclophilin B as a chaperone to proteins destined for the plasma membrane, rather than solely as a proline isomerase functioning within the endoplasmic reticulum.

A map of the distal region of the long arm of human chromosome 21 constructed by radiation hybrid mapping and pulsed-field gel electrophoresis

We have used radiation hybrid (RH) mapping and pulsed-field gel electrophoresis (PFGE) to determine the order and positions of 28 DNA markers from the distal region of the long arm of human chromosome 21. The maps generated by these two methods are in good agreement. This study, combined with that of D. R. Cox et al. (1990, Science 250:245-250), results in an RH map that covers the long arm of chromosome 21 (21q). We have used a subtelomeric probe to show that our map includes the telomere and have identified single-copy genes and markers within 200 kbp of the telomere. Comparison of the physical and RH maps with genetic linkage maps shows "hot spots" of meiotic recombination in the distal region, one of which is close to the telomere, in agreement with previous cytogenetic observations of increased recombination frequency near telomeres.

Radiation hybrid mapping: a somatic cell genetic method for constructing high-resolution maps of mammalian chromosomes

Radiation hybrid (RH) mapping, a somatic cell genetic technique, was developed as a general approach for constructing long-range maps of mammalian chromosomes. This statistical method depends on x-ray breakage of chromosomes to determine the distances between DNA markers, as well as their order on the chromosome. In addition, the method allows the relative likelihoods of alternative marker orders to be determined. The RH procedure was used to map 14 DNA probes from a region of human chromosome 21 spanning 20 megabase pairs. The map was confirmed by pulsed-field gel electrophoretic analysis. The results demonstrate the effectiveness of RH mapping for constructing high-resolution, contiguous maps of mammalian chromosomes.

Experimental residency program in veterinary public health

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