Comparative analysis of thyroid carcinoma in Germany and the U.S

[Bethesda classification of fine needle punctures of the thyroid. Much ado about nothing really new?]

The Bethesda system for reporting thyroid cytopathology was published in 2008 (Baloch et al. 2008, Cytojournal 5:6; Baloch et al. 2008, Diagn Cytopathol 36:425-437) offering a classification system which is closely related to clinical data. The aim was to ensure adequate terminology without risk of errors in understanding, to advise clinicians concerning therapeutic options in relationship to cytological diagnoses as well as to facilitate the comparison of cytology data at national and international levels. However, mainly due to specific US American (both medical and legal) demands, this classification system is not yet fully appreciated in most European countries. The reasons are various: (a) Criteria for representative material are much more restrictive than those commonly used and in Germany a higher number of (unnecessary) repunctures would be the consequence. (b) It remains doubtful whether the introduction of a new and rather heterogeneous category of "atypia of undetermined significance or follicular lesion of undetermined significance" would contribute to a substantial decrease of findings classified as "follicular neoplasia". Furthermore it is unlikely that clinicians would be willing to accept the recommended conservative approach with repuncture if a new diagnostic category is associated with a calculated risk of malignancy in 5-15% cases. (c) Until now an integration of new developments in molecular markers into the Bethesda system is missing. Thus, for experienced cytologists the Bethesda system for reporting thyroid cytopathology offers very limited benefits in comparison to the currently used, established and highly accepted classification systems. However, a positive argument remains the fact that an internationally accepted classification system may improve the comparability of the results of national and international studies on thyroid findings.

Classification of follicular cell tumors of the thyroid gland: analysis involving Japanese patients from one institute

Prognostic analyses of thyroid carcinomas of follicular cell origin were carried out on patients treated at Kuma Hospital, Kobe, Japan. A new histopathological classification based on the prognostic evidence is proposed in this study, and it is applicable to the patients treated curatively. Major histological types of papillary carcinoma, follicular carcinoma and poorly differentiated carcinoma were combined into one single entity of follicular cell adenocarcinoma because (i) they have the same cell origin (follicular cell); (ii) clear-cut separation of papillary and follicular carcinoma is not always possible, and 10 year cause-specific survival was essentially similar when the patients were treated curatively; and (iii) poorly differentiated carcinoma usually has a background of either papillary or follicular carcinoma. This adenocarcinoma together with undifferentiated carcinoma was stratified into four prognostic groups using pure morphological criteria of the degree of cellular differentiation and histological grade. They are termed well-differentiated adenocarcinoma, moderately differentiated adenocarcinoma, poorly differentiated carcinoma and undifferentiated carcinoma of the thyroid. The 10 year disease-free survival rates were 86.3-93.1%, 65.4-78.7%, and 43.0-53.8%, and 0%, respectively. The 10 year cause-specific survival rates were 97.2-100%, 91.5-97.4%, and 71.2-80.0%, and 0%, respectively.

Application of staging systems for differentiated thyroid carcinoma in an endemic goiter region with iodine substitution

OBJECTIVE

To evaluate and compare staging systems for differentiated thyroid carcinoma and predicted outcome in an endemic goiter region with iodine substitution and to examine the risk profile of differentiated thyroid carcinoma and compare it against nongoiter regions.

SUMMARY BACKGROUND DATA

Differentiated (papillary or follicular) thyroid carcinoma has a favorable prognostic outcome. In numerous studies prognostic factors have been identified and staging systems created, particularly in Anglo-American centers (nonendemic goiter regions), to evaluate individual prognostic outcome.

METHODS

In a retrospective study, the authors assessed 440 patients with differentiated thyroid carcinoma (papillary, n = 293; follicular, n = 147) and a long-term follow-up of median 10.6 years to determine the predictive accuracy of nine staging systems applicable to the study population; the systems were compared by calculating the proportion of variation explained.

RESULTS

With regard to cause-specific mortality, the difference between the respective stages and/or risk groups was highly significant for every staging system. By means of calculating the proportion of variation explained, MACIS scoring supplied the most reliable prognostic information for differentiated thyroid carcinoma (relative importance 16.93%). EORTC and UICC/AJCC systems had a relative importance of 16.34% and 13.96%, respectively, also a high level of accuracy; this implies that they are superior to the other six staging systems. If we separate papillary and follicular carcinoma, for the former the MACIS score with a relative importance of 15.05% is clearly superior to the other staging systems, whereas for the latter the EORTC score and the UICC/AJCC staging system, with relative importance of 17.04% and 16.58%, respectively, yield the best prognostic information.

CONCLUSIONS

By applying staging systems in an endemic goiter region with iodine substitution, the best prognostic information for papillary thyroid carcinoma has been achieved with the MACIS score, while for follicular thyroid carcinoma the EORTC score and the UICC/AJCC system have the best prognostic accuracy. Because of the individual factors, which are easy to obtain and generally available (age, T, N, M classification), the uncomplicated handling, and the widespread use and the good predictive accuracy, the UICC/AJCC classification is the staging system of choice for comparing published results.