Assessment of the effect of the American Society of Breast Surgery guidelines on contralateral prophylactic mastectomy rates for unilateral breast cancer.

BACKGROUND: In July 2016, the American Society of Breast Surgeons published guidelines discouraging contralateral prophylactic mastectomy for average-risk women with unilateral breast cancer. We incorporated these into practice with structured patient counseling and aimed to assess the effect of this initiative on contralateral prophylactic mastectomy rates. METHODS: We evaluated female patients with unilateral breast cancer undergoing mastectomy at our institution from January 2011 to November 2022. Variables associated with contralateral prophylactic mastectomy and trends over time were analyzed using the Wilcoxon rank sum test or χ2 analysis as appropriate. RESULTS: Among 3,208 patients, (median age 54 years) 1,366 (43%) had a unilateral mastectomy, and 1,842 (57%) also had a concomitant contralateral prophylactic mastectomy. Across all patients, contralateral prophylactic mastectomy rates significantly decreased post-implementation from 2017 to 2019 (55%) vs 2015 to 2016 (62%) (P = .01) but increased from 2020 to 2022 (61%). Immediate breast reconstruction rate was 70% overall (81% with contralateral prophylactic mastectomy and 56% without contralateral prophylactic mastectomy, P < .001). Younger age, White race, mutation status, and earlier stage were also associated with contralateral prophylactic mastectomy. Genetic testing increased from 27% pre-guideline to 74% 2020 to 2022, as did the proportion of patients with a pathogenic variant (4% pre-guideline vs 11% from 2020-2022, P < .001), of whom 91% had a contralateral prophylactic mastectomy. Among tested patients without a pathogenic variant and patients not tested, contralateral prophylactic mastectomy rates declined from 78% to 67% and 48% to 38% pre -and post-guidelines, respectively, P < .001. CONCLUSION: Implementation of specific patient counseling was effective in decreasing contralateral prophylactic mastectomy rates. While recognizing that patient choice plays a significant role in the decision for contralateral prophylactic mastectomy, further educational efforts are warranted to affect contralateral prophylactic mastectomy rates, particularly in the setting of negative genetic testing.

Lack of Clinical Value for Immunohistochemistry for Sentinel Lymph Node Assessment in Invasive Lobular Carcinoma.

BACKGROUND: The distinct histologic appearance of invasive lobular carcinoma (ILC) may pose diagnostic challenges for sentinel lymph node (SLN) analysis. We evaluated the impact of cytokeratin immunohistochemistry (IHC) on SLN assessment in ILC and its contribution to pathologic nodal upstaging. METHODS: We identified ILC patients treated with SLN surgery at our institution between September 2008 and August 2021. IHC for SLN assessment was employed at the discretion of the pathologist. Differences between groups evaluated with and without IHC were compared using Chi-square tests. RESULTS: Overall, 608 cases of ILC were identified in patients who underwent SLN surgery. IHC was used in 301 cases (49.5%) and was not associated with cT category, pT category, or tumor grade. Use of IHC increased detection of SLN+ disease when isolated tumor cells (ITCs) were included in the analysis (35.9% with IHC vs. 21.2% without IHC; p < 0.001). There was no effect on nodal upstaging to micrometastatic disease (pN1mi) or greater (21.9% with IHC vs. 21.2% without IHC; p = 0.82). IHC did not increase the number of positive SLNs detected (median 1 with and without IHC) nor did it increase axillary lymph node dissection (ALND) rates (11.6% with IHC vs. 15.3% without IHC; p = 0.18). CONCLUSION: IHC improved detection of pN0(i+) disease among ILC patients undergoing SLN surgery. IHC did not increase upstaging to pN1mi or higher categories of nodal disease, detection of a greater number of positive SLNs, or ALND rates. Our data suggest routine use of IHC for SLN assessment in ILC patients does not add clinical utility.

MRI Radiomics for Assessment of Molecular Subtype, Pathological Complete Response, and Residual Cancer Burden in Breast Cancer Patients Treated With Neoadjuvant Chemotherapy.

RATIONALE AND OBJECTIVES: There are limited data on pretreatment imaging features that can predict response to neoadjuvant chemotherapy (NAC). To extract volumetric pretreatment MRI radiomics features and assess corresponding associations with breast cancer molecular subtypes, pathological complete response (pCR), and residual cancer burden (RCB) in patients treated with NAC. MATERIALS AND METHODS: In this IRB-approved study, clinical and pretreatment MRI data from patients with biopsy-proven breast cancer who received NAC between September 2009 and July 2016 were retrospectively analyzed. Tumors were manually identified and semi-automatically segmented on first postcontrast images. Morphological and three-dimensional textural features were computed, including unfiltered and filtered image data, with spatial scaling factors (SSF) of 2, 4, and 6 mm. Wilcoxon rank-sum tests and area under the receiver operating characteristic curve were used for statistical analysis. RESULTS: Two hundred and fifty nine patients with unilateral breast cancer, including 73 (28.2%) HER2+, 112 (43.2%) luminal, and 74 (28.6%) triple negative breast cancers (TNBC), were included. There was a significant difference in the median volume (p = 0.008), median longest axial tumor diameter (p = 0.009), and median longest volumetric diameter (p = 0.01) among tumor subtypes. There was also a significant difference in minimum signal intensity and entropy among the tumor subtypes with SSF = 4 mm (p = 0.009 and p = 0.02 respectively) and SSF = 6 mm (p = 0.007 and p < 0.001 respectively). Additionally, sphericity (p = 0.04) in HER2+ tumors and entropy with SSF = 2, 4, 6 mm (p = 0.004, 0.02, 0.047 respectively) in luminal tumors were significantly associated with pCR. Multiple features demonstrated significant association (p < 0.05) with pCR in TNBC and with RCB in luminal tumors and TNBC, with standard deviation of intensity with SSF = 6 mm achieving the highest AUC (AUC = 0.734) for pCR in TNBC. CONCLUSION: MRI radiomics features are associated with different molecular subtypes of breast cancer, pCR, and RCB. These features may be noninvasive imaging biomarkers to identify cancer subtype and predict response to NAC.

Predicting four or more metastatic axillary lymph nodes in patients with sentinel node-positive breast cancer: assessment of existent risk scores.

BACKGROUND: Patients with metastases in four or more axillary lymph nodes (≥4+ALN) represent a subset of patients with breast cancer who are at increased risk of local recurrence and who benefit from postmastectomy radiation. Risk prediction models designed to identify such patients have been published by Rivers et al., Chagpar et al., and Katz et al. We sought to evaluate and compare the performance of these models in an independent patient population. METHODS: We reviewed 454 patients with breast cancer with one to three positive sentinel lymph nodes who underwent completion axillary lymph node dissection at our institution. Each of the three published models was applied to our sample as described in the respective publications. The models' performances were analyzed with the Hosmer-Lemeshow goodness-of-fit test and with the area under the curve (AUC). Sensitivity, specificity, and false-negative percentages were calculated for clinically meaningful cutoff points of each score. RESULTS: Of 454 eligible patients, 87 (19.2%) had four or more positive axillary nodes. The Rivers, Chagpar, and Katz models demonstrated good calibration in our population based on the Hosmer-Lemeshow test (p = 0.82, p = 0.73, p = 0.71, respectively). Assessment of discriminatory ability for the models resulted in AUCs of 0.81, 0.73, and 0.81, respectively. CONCLUSIONS: The Rivers and Katz models performed well in our patient population and may be clinically useful to predict patients with ≥4+ALN. However, their clinical utility is limited by the current controversy surrounding the use of postmastectomy radiation for all node-positive patients.

Assessment of the performance of the Stanford Online Calculator for the prediction of nonsentinel lymph node metastasis in sentinel lymph node-positive breast cancer patients.

BACKGROUND: Several models for the prediction of nonsentinel lymph node (NSLN) metastasis in sentinel lymph node (SLN)-positive breast cancer patients have been proposed. In this study, the authors evaluate the Stanford Online Calculator (SOC), which was designed to predict the likelihood of NSLN metastasis using only 3 variables: primary tumor size, SLN metastasis size, and angiolymphatic invasion status. They compared it with the Mayo and Memorial Sloan-Kettering Cancer Center (MSKCC) nomograms. METHODS: The SOC was used to calculate the probability of NSLN metastasis in 464 breast cancer patients with SLN metastasis who underwent completion axillary lymph node dissection at the Mayo Clinic. The area under the receiver operating characteristic curve (AUC) was calculated for each model. Mean probabilities of patients with and without NSLN metastasis were compared. Patients with

Assessment of cardiovascular risk status at CT colonography.

PURPOSE: To retrospectively determine whether calcium scores of the abdominal aorta obtained during computed tomographic (CT) colonography relate to Framingham risk factors and clinical cardiac events. MATERIALS AND METHODS: The institutional review board approved the current HIPAA-compliant retrospective study and waived informed consent. Between 1995 and 1998, 480 patients underwent CT colonography; 467 patients were available for assessment. Calcium scores with a threshold attenuation value of 130 HU or greater were recorded for abdominal aorta (suprarenal, infrarenal, and aortic bifurcation regions and total). Patient histories were abstracted for established cardiac risk factors and subsequent cardiac events. Associations between calcium measurements and binary risk factors were assessed with Wilcoxon rank sum test; those with continuous risk factors, with Spearman rank correlation coefficient; and those with combined end points, with Cox proportional hazards model. RESULTS: Follow-up data were available for 467 patients with median age of 65 years (range, 34-83 years); 59% (275 of 467) were men. Nine patients had cardiac events subsequent to CT colonography. Results of proportional hazards regression analysis revealed a significant association between myocardial infarction or cardiac event-related death and calcium scores of the aortic bifurcation that exceeded 895, the value for the 75th percentile for this calcium variable (P < .01). Associations with established cardiac risk factors for all four calcium scores were significant (P < .05). Spearman rank correlation coefficients for associations between total calcium score and patient characteristics of age, number of pack-years of smoking, and systolic blood pressure were 0.51, 0.43, and 0.29, respectively (P < .001 for all). CONCLUSION: Aortic calcification scores at CT colonography are significantly associated with established cardiac risk factors and cardiac-related events. This screening information can be obtained without additional scanning or risk to the patient.