[Significance of lymph node metastases of differentiated thyroid gland carcinomas and C-cell carcinomas for prognosis--a meta-analysis].

Surgical therapy of differentiated thyroid cancer (DTC) includes thyroidectomy plus central lymph node dissection and postoperative radioiodine therapy. In cases of lymph node metastasis, T3/T4 tumors and C-cell-carcinoma (after thyroidectomy) uni- or bilateral modified radical lymph node dissection of the neck (neck dissection) and of the mediastinum is recommended. The importance of lymph node metastasis for prognosis of survival in papillary, follicular and C-cell-carcinoma is discussed controversial, however. Even the kind of surgical radicality is questioned. Thus a metaanalysis of 35 studies in 29 independent publications from a pool of 2186 studies was performed. Univariate analysis demonstrates lymph node metastasis as a negative prognostic factor in papillary carcinoma with a 3.25/2.97, in follicular carcinoma with a 7.62/4.0 and in C-cell-carcinoma with a 3.33/3.37 higher probability of mortality 5 and 10 years after operation. Modification of the present surgical therapy can therefore only be accepted after univariate and multivariate analysis of all prognostic factors (age, sex, cell type, tumor extent, lymph node- and distant metastasis) and after it has proven superiority to the present strategy in prospective randomised trials.