Podcast
Questions and Answers
What is the goal of achieving a clear margin in lumpectomy?
What is the goal of achieving a clear margin in lumpectomy?
What is the Gold Standard in assessing the performance of MarginProbe?
What is the Gold Standard in assessing the performance of MarginProbe?
What is the purpose of ink seeping in evaluating lumpectomy margins?
What is the purpose of ink seeping in evaluating lumpectomy margins?
What is the purpose of assessing the margin in lumpectomy?
What is the purpose of assessing the margin in lumpectomy?
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What is the final step in the pathologic processing of a breast specimen?
What is the final step in the pathologic processing of a breast specimen?
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What is the significance of achieving a clear margin in lumpectomy?
What is the significance of achieving a clear margin in lumpectomy?
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What is the first step in the pathologic processing of a breast specimen?
What is the first step in the pathologic processing of a breast specimen?
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What is the purpose of final histopathology in assessing the performance of MarginProbe?
What is the purpose of final histopathology in assessing the performance of MarginProbe?
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What is the re-excision rate in the control group in the study by Schnabel?
What is the re-excision rate in the control group in the study by Schnabel?
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Which of the following studies showed a 62% reduction in positive margins?
Which of the following studies showed a 62% reduction in positive margins?
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What is the cosmetic outcome reported in the Thill study?
What is the cosmetic outcome reported in the Thill study?
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In the study by Allweis, what was the re-excision rate in the MarginProbe group?
In the study by Allweis, what was the re-excision rate in the MarginProbe group?
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What is the relative reduction in re-excision rates reported in the study by Kupstas?
What is the relative reduction in re-excision rates reported in the study by Kupstas?
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Which of the following studies reported a 30.8% re-excision rate in the control group?
Which of the following studies reported a 30.8% re-excision rate in the control group?
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What is the significance of a clear margin in lumpectomy?
What is the significance of a clear margin in lumpectomy?
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What is the impact of reoperation rates on breast conservation therapy?
What is the impact of reoperation rates on breast conservation therapy?
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What is the role of predicting reexcision findings in breast conservation therapy?
What is the role of predicting reexcision findings in breast conservation therapy?
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What percentage of cases may require reoperation for positive margins after BCS?
What percentage of cases may require reoperation for positive margins after BCS?
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What is the consequence of having positive margins in lumpectomy?
What is the consequence of having positive margins in lumpectomy?
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What is the standard practice regarding tumor cells at the margin of the excised specimen?
What is the standard practice regarding tumor cells at the margin of the excised specimen?
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What percentage of main lumpectomy specimens may have positive or close margins?
What percentage of main lumpectomy specimens may have positive or close margins?
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What is the recommended course of action for patients not amenable to margin-free lumpectomy?
What is the recommended course of action for patients not amenable to margin-free lumpectomy?
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Study Notes
Diagnostic Testing
- A diagnostic test aims to identify a disease or condition to enable its clinical management
- The performance of a diagnostic test is characterized by two key concepts: Sensitivity and Specificity
Sensitivity and Specificity
- Sensitivity: the probability that a diagnostic test will identify disease when disease is present
- Specificity: the probability that a diagnostic test will identify healthy tissue when healthy tissue is present
MarginProbe
- MarginProbe is a diagnostic test that seeks to identify cancerous tissue
- The test can produce four possible outcomes: True Positive, False Positive, True Negative, and False Negative
- Sensitivity and Specificity are calculated using the following formulas:
- Sensitivity: TP/(TP+FN)
- Specificity: TN/(TN+FP)
False Positive and False Negative Rates
- False Positive Rate: the probability that a diagnostic test will incorrectly identify healthy tissue as cancerous
- False Negative Rate: the probability that a diagnostic test will incorrectly identify cancerous tissue as healthy
- False Positive Rate = 1-Specificity
- False Negative Rate = 1-Sensitivity
PPV and NPV
- PPV (Positive Predictive Value): the probability that a positive test result is a true positive
- NPV (Negative Predictive Value): the probability that a negative test result is a true negative
Pathology
- Pathology is the study and diagnosis of disease through the examination of surgically removed organs, tissues, bodily fluids, or autopsy
- Surgical Pathology involves macroscopic and microscopic tissue analysis
- Cytopathology examines free cells or tissue fragments
- Molecular Pathology studies and diagnoses disease through examination of molecules within organs, tissues, or bodily fluids
Evaluation of Lumpectomy Margins
- Lumpectomy margins are evaluated to achieve a pathologically clear margin
- The Gold Standard for assessing MarginProbe performance is final histopathology
Diagnostic Testing Concepts
- A diagnostic test seeks to identify a disease or condition to enable its clinical management.
- The performance of a diagnostic test is characterized by its accuracy, sensitivity, and specificity.
Sensitivity and Specificity
- Sensitivity is the probability that a diagnostic test will identify disease when disease is present.
- It measures the proportion of true positives (correctly identified disease cases) among all actual disease cases.
- Example: In a patient with a positive margin, what is the probability that MarginProbe will call it positive?
Specificity
- Specificity is the probability that a diagnostic test will identify healthy tissue when healthy tissue is present.
- It measures the proportion of true negatives (correctly identified healthy tissue cases) among all actual healthy tissue cases.
- Example: In a patient with a clear margin, what is the probability that MarginProbe will call it negative?
MarginProbe Performance
- MarginProbe performance is evaluated by comparing its results to the Gold Standard (final histopathology).
- The Gold Standard is the accepted true description of tissue and margin.
- MarginProbe's sensitivity and specificity can be calculated using formulas: TP/(TP+FN) for sensitivity, and TN/(TN+FP) for specificity.
Pathology
- Pathology is the study and diagnosis of disease through the examination of surgically removed organs, tissues, bodily fluids, or autopsy.
- Surgical Pathology involves macroscopic and microscopic tissue analysis.
- Cytopathology studies and diagnoses disease on a cellular level, while Molecular Pathology identifies mutations or alterations in the genetic code of a patient.
Lumpectomy Margins
- Successful lumpectomy is predicated on achieving a pathologically clear margin.
- Pathologic processing of a breast specimen involves orientation, specimen inking, gross assessment, paraffin embedding, and slicing for microscopic examination.
Breast Conservation Therapy
- Positive margins in breast-conserving surgery (BCS) are associated with patient discomfort, increased costs, and poorer cosmetic outcomes.
- Up to 50% of BCS cases may require reoperation due to positive margins.
Standard of Care (SOC)
- SOC intraoperative methods to evaluate margin status include palpation, specimen imaging, and intraoperative gross and/or microscopic pathology assessment.
Margin Definition
- There is no consensus on the required distance of tumor from the cut edge to define a positive margin.
- Positive/close margins may be defined anywhere between tumor at the inked margin to tumor within 5 mm of the inked margin.
Surgical Margin and Re-excision
- Patients not amenable to margin-free lumpectomy should undergo mastectomy.
- Up to 54% of main lumpectomy specimens may have positive or close margins, requiring re-excision.
MarginProbe Study
- A prospective, randomized, controlled, multicenter study evaluated the use of a real-time, intraoperative probe for positive margin detection in breast-conserving surgery.
- Surgeons were allowed to use any standard of care (SOC) intraoperative methods to evaluate margin status.
- Pathology data were collected for the primary lumpectomy and all repeat ipsilateral surgical procedures within 6 months.
Cosmetic Evaluation
- Cosmetic evaluation was performed at baseline, 7-30 days, and 3-6 months following surgery by an observer unaware of the patient's randomization assignment.
- A symmetry-based scale was used for assessment.
Study Results
- The study demonstrated a significant and consistent reduction in positive margins and re-excision rates.
- A relative reduction of 23% re-excision rates and 62% margins were observed.
- Cosmesis was maintained or improved in the study group.
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Description
Understand the fundamental concepts in diagnostic testing, including accuracy, sensitivity, and false positive rates. Learn how to evaluate the reliability of test results.
