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Improving the reproducibility of diagnosing micrometastases and isolated tumor cells†
Article first published online: 8 DEC 2004
Copyright © 2004 American Cancer Society
Volume 103, Issue 2, pages 358–367, 15 January 2005
How to Cite
Cserni, G., Bianchi, S., Boecker, W., Decker, T., Lacerda, M., Rank, F., Wells, C. A. and for The European Working Group for Breast Screening Pathology (2005), Improving the reproducibility of diagnosing micrometastases and isolated tumor cells. Cancer, 103: 358–367. doi: 10.1002/cncr.20760
This project would not have been possible without the organizers (Dr. Fritz Rank and Professors Simonetta Bianchi and Werner Boecker) or without the sponsors of the Copenhagen, Florence, and Münster meetings of the European Working Group for Breast Screening Pathology: Ethicon Endo-Surgery Breast Care (Italy), Leica Microsystems S.p.A. (Milan, Italy), and the German screening program.
- Issue published online: 5 JAN 2005
- Article first published online: 8 DEC 2004
- Manuscript Accepted: 21 SEP 2004
- Manuscript Revised: 9 SEP 2004
- Manuscript Received: 7 JUL 2004
- Hungarian Ministry of Health. Grant Number: ETT 176/01
- János Bolyai Research Fellowship from the Hungarian Academy of Sciences
- isolated tumor cells;
- kappa statistics;
- sentinel lymph node;
- tumor-lymphnode-metastasis (TNM)
The latest edition of the tumor-lymph node-metastasis (TNM) classification of malignant tumors distinguishes between isolated tumor cells (pN0) and micrometastases (pN1mi). The reproducibility of these categories has not been assessed previously.
Digital images from 50 cases with low-volume lymph node involvement from axillary sentinel lymph nodes were circulated twice for evaluation (Evaluation Rounds 1 and 2) among the members of the European Working Group for Breast Screening Pathology, and the members were asked to categorize lesions as micrometastasis, isolated tumor cells, or something else and to classify each case into a pathologic lymph node (pN) category of the pathologic TNM system. Methods for improving the low reproducibility of the categorizations were discussed between the two evaluation rounds. κ Statistics were used for the assessment of interobserver variability.
The κ value for the consistency of categorizing low-volume lymph node load into micrometastasis, isolated tumor cells, or neither of those changed from 0.39 to 0.49 between Evaluation Rounds 1 and 2, but it was slightly lower for the pN categories (0.35 and 0.44, respectively). Interpretation of the definitions of isolated tumor cells (especially with respect to their localization within the lymph node), lack of guidance on how to measure them if they were multiple, and lack of any definitions for multiple simultaneous foci of lymph node involvement were listed among the causes of discordant diagnoses.
The results of the current study indicated that the definitions available have minor contradictions and do not permit a reproducible distinction between micrometastases and isolated tumor cells. Refinement of these definitions, therefore, is required. One refinement that may improve reproducibility is suggested in this report. Cancer 2005. © 2004 American Cancer Society.