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Improving the reproducibility of diagnosing micrometastases and isolated tumor cells
Author(s) -
Cserni Gábor,
Bianchi Simonetta,
Boecker Werner,
Decker Thomas,
Lacerda Manuela,
Rank Fritz,
Wells Clive A.
Publication year - 2005
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/cncr.20760
Subject(s) - micrometastasis , medicine , lymph node , lymph , reproducibility , pathology , axillary lymph nodes , kappa , sentinel lymph node , breast cancer , radiology , oncology , cancer , statistics , mathematics , linguistics , philosophy
BACKGROUND 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.