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INTRODUCTION: Choosing Wisely (CW) recommends women age ≥70 y with cT1-2cN0 ER+/HER2-invasive breast cancer (BC) should forgo routine axillary staging with sentinel lymph node biopsy (SLN) at the time of breast surgery. Despite this longstanding recommendation, acceptance of SLN omission has not been widely adopted. Genomic assays, such as MammaPrint (MP), may supplement the decision to apply CW. We hypothesized that having MP on BC core needle biopsy (CNB) meeting CW could provide additional information to aid in decision-making about the need for axillary staging with SLN. METHODS: A retrospective single-institution review was conducted for women with BC meeting CW criteria, who also had MP performed on CNB from 2020 to 2021. Categorical characteristics were compared using the chi-square test. Continuous variables were compared using the Mann-Whitney U-test. RESULTS: MP was available on CNB for 238 BC meeting CW criteria: 70% low risk and 30% high risk. Axillary staging was performed in 195 (82%). Eighty-one percent were pathologically node-negative and 19% were pathologically node-positive. The MP score did not correlate with pathologic nodal stage (P = 0.52). The rate of high nodal burden (pN2) was extremely low (n = 1, 0.5%). The only significant correlation with pathological node positivity was older age (P = 0.03). Appropriately, high-risk MP was strongly associated with increased recurrence risk (n = 4, P = 0.008). CONCLUSIONS: Having MP on CNB does not provide clinically meaningful information about the pN stage and does not further refine which BC patients within CW could benefit from escalation to SLN or delineate a group more likely to be pathologically node-negative.
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BACKGROUND: Drug-eluting stents deliver potent compounds directly to arterial segments but can become clot laden when deployed. The question arises as to whether thrombi affect drug elution and arterial uptake. METHODS AND RESULTS: Paclitaxel transport and retention were assessed in clots of different blood components. Diffusivity, affected by clot organization, is fastest in fibrin (approximately 347 microm2/s), slower in fibrin-red blood cell clots (34.98 microm2/s), and slowest in whole-blood clots (3.55 microm2/s). Blood cells bind and retain paclitaxel such that levels in clot increase linearly with red cell fraction. At physiological hematocrit, clot retains 3 times the amount of paclitaxel in surrounding solutions. Computational models predict that the potential of thrombus to absorb, retain, and release drug or to act as a barrier to drug delivery depends on clot geometry and strut position in clot relative to the vessel wall. Clot between artery and stent can reduce uptake 10-fold, whereas clot overlying the stent can shield drug from washout, increasing uptake. Model assumptions were confirmed and predictions were validated in a novel rat model that introduces thrombosis within stented aortas where nonocclusive thrombus acts as capacitive space for drug and shifts drug levels to decrease tissue uptake 2-fold. CONCLUSIONS: Thrombus apposed on stents creates large variations in drug uptake and can act to either increase or decrease wall deposition according to the clot and stent geometry. Arterial deposition of drug from stents deployed in clots will be highly variable and unpredictable unless the clot can be adequately controlled or removed.
