Pathological Evaluation of Sentinel Lymph Node Biopsy in Breast Cancer

1. Pathological Evaluation of Sentinel Lymph Node Biopsy in Breast Cancer N. Krishnani Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow These PowerPoint presentations are free to download only for academic purposes, with due acknowledgements to authors and this website.

2. Sentinel Lymph Node • First node to which lymph drainage and metastasis from breast cancer occurs • Central group of level I (most common) • Level II or III • Intramammary • Interpectoral or internal mammary node Proceedings of the Consensus Conference on Role of SLNB, 2001 Philadelphia

3. Sentinel Lymph Node • Represent the entire nodal basin • Most likely to contain tumor if metastasis has occurred • If sentinel nodes are patholgically benign, all of the other axillary nodes can be considered tumor free • SLNB is suitable replacement for axillary dissection as a staging and diagnostic procedure in T1 andT2 breast cancers

4. Sentinel Lymph Node Approximately 40% of operable breast cancer have axillary disease according to conventional histological methods • Stage Positive SLN • T1a 4.3% • T1b 19.5% • T1c 23.8% • T2 48.9% • T3 66.7%

5. Inclusion and Exclusion Criteria • Stage T1 or T2 disease without palpable nodal metastases • Palpable axillary node metastases • Multifocal breast cancer • Pregnancy or currently breast feeding • Prior major breast or axillary operations • Allergies to blue dye or radiocolloid Proceedings of the Consensus Conference on Role of SLNB, 2001 Philadelphia

6. Sentinel Node Biopsy in Ductal Carcinoma In-situ • Not indicated in mammographically detected DCIS or incidental finding. • Indications: • Palpable mass • Large areas of calcification • large lumpectomy • High grade with or without comedo necrosis • (microinvasion may be overlooked because of the area of disease is so large)

7. Handling of Specimen • Measured and cut along its longitudinal axis into 2 mm-thick sections • Gross examination to detect focal lesions • Each 2 mm thick sections be cut at three levels • Imprint cytology smears are prepared • Remaining lymph node sections are then submitted for paraffin section histology • Each paraffin block should be sectioned at 3 levels • Report include individual cell / colonies / large size and location of malignant cells Proceedings of the Consensus Conference on Role of SLNB, 2001 Philadelphia

8. 2 mm 2-3 mm Am J Surg Pathol 2003;27(3):385-389

9. Am J Surg Pathol 2003; 27(3):385-389

10. Metastases Macrometastases: Any tumor deposit > 2mm Micrometastases: Cohesive cluster of malignant cells, 0.2 mm and upto and including 2.0 mm in diameter. Indicate residual disease in approx. 10% of patients Sub-micrometastases: Clusters of malignant cells measuring less than 0.2 mm. Seen by IHC No clinical significance and highly unlikely to be associated with significant residual metastasis and predict an adverse outcome

14. Frozen Section Advantages Interpretation of nodal architecture available More specific diagnosis possible Size of metastatic focus measurable Can be complemented by rapid IHC Histologists are more familiar with the method Disadvantages Relatively time-consuming More expensive Freezing artifacts Some tissue is lost More expensive

15. Imprint Cytology Advantages Simple / cheap / rapid Interpretation of cytological / nuclear details available Avoid tissue loss Can be complemented by IHC Disadvantages Size and area of metastatic focus not detectable More indeterminate / deferred diagnoses Need special training to interpret Can not differentiate between micro and macrometastases

16. Intraoperative Frozen-section Diagnosis

17. Multiple Levels of H&E Sections

18. Intraoperative Imprint Cytology

19. Intraoperative Cytology • Diagnostic accuracy did not exceed that of frozen section • Occasional false positive case • Concordance rate is approx. 90% • When both method employed, diagnostic accuracy improve Takeshi Nagashima et al, Acta Cytol 2003;47:1028-1032

20. Immunohistochemical Technique • More accurate and used as adjunct to routine stain • Antibody to cytokeratin used to detect small focus of malignant cells (Micrometastases or isolated tumor cells) • False positive • Benign transport of breast epithelium • Degenerating cells in transit • Dendritic cells • Macrophages • Epidermal squamous cells

29. Immunohitochemical Staining

30. H&E and Immunohistochemistry Probability of non-SLN metastasis will be less than 0.1% if SLN negativity is confirmed by both H&E and immunohistochemistry Turner et al: Am J Surg Pathol 1999;23:263-267

31. Implications of Micrometastases Seen Only on Immunohistochemistry • What is the significance of occult metastases in terms of prognosis • What is the significance of occult metastases in terms of predicting further nodal involvement (approx. 12%) • Do these patient stand to benefit from completion axillary lymph node dissection and / or systemic chemotherapy

32. Implications of Micrometastasies Seen Only on Immunohistochemistry • Data are inconclusive at this time • Additional studies are needed in order to establish the role of IHC detected lymph node metastases

33. Recommendations • Ignore the presence of isolated tumor cells • Either refrain from examining SLN by IHC or address on case by case basis • Allweis et al, Breast 2003;12:163-167 and European Consensus group for Breast Screening Pathology

34. Recommendations • Standard practice and, the pathology report should state only whether metastasis are found on H&E stained slide • IHC may be performed when the H&E stained slides have suspicious cells that are equivocal • Cytokeratin positive malignant cells be quantified • Proceedings of the Consensus Conference on Role of SLNB, 2001 Philadelphia

35. Recommendations Adjuvant therapy, either chemotherapy or hormonal treatment (or for completion axillary dissection or axillary radiation) should not be made solely on the basis of information obtained by IHC of sentinel lymph node Proceedings of the Consensus Conference on Role of SLNB, 2001 Philadelphia

36. Molecular Analysis • Assesment by reverse transcription-polymerase chain reaction (RT-PCR) • More sensitive than immunohistochemistry • Specific markers are lacking, and false negative tests • Relevance is even more debatable than occult metastasis detected by immunohistochemistry • Results are highly variable and high rate of upstaging (14-50%) • Experimental assessment • Not feasible in all pathology lab

37. Summary of Consensus • Intraoperative assessment of SNs is strongly recommended • Careful handling specimen and cut node into 2 mm section and examine for any focal lesion • Step sectioning or multiple level assessment should be used, although the optimal distance between these step is controversial • Choice of method should be institutional depending on the resources • Imprint cytology should be done in conjunction with frozen section

38. Summary of Consensus • Immunohistochemistry is optional in routine patient management • Molecular analysis be restricted to research purposes as controversies over the interpretation and the lack of specific markers