[Belgian registry of thyroid cancer. Preliminary epidemiological characteristics revealed by a retrospective study (1988-1995). Belgian Thyroid Cancer Study Group].

The aim of a cancer registry is to study the incidence of cancer in a well-determined population and to allow epidemiological research to the setting up of diagnosis and therapeutic strategies. The Belgian Thyroid Cancer Study Group (BTCSG) was founded in 1990. In the present study we report data collected from 1988 to 1995 in 397 patients with a differentiated (papillary and follicular) thyroid carcinoma living in the french-speaking area of Belgium. The sex ratio female/male is 3.5 and the median ages at the diagnosis, is similar (45 yrs, 12-82) in both sexes. Seven cases of thyroid cancer were registered in young patients less than 18 yrs old. Thyroid carcinoma were associated with multinodular goiter in more than 50% cases. Cancer was bilateral in 17%. Papillary histological type accounts for 84% in our series while its diagnosis was established in 45% at early clinical stages (TO-T1). These observations could probably be related with 1) broader indications and more aggressive options for the surgical removal of diffuse multinodular goiter, 2) more sophisticated pathologic examinations that might have led to the detection of a greater incidence of occult carcinomas, incidentally discovered. Lymph nodes metastases were present at the time of diagnosis in 20%, especially in young patients. The risk for local and/or lateral recurrence or distant metastases is significantly related to the size of the tumor, histologically verified lymph node metastases and the values of the EORTC prognostic index (> or = 50) that additionally takes into account the differentiation of the tumor. Considering our short median follow-up time of 25 months, it is currently too early to define if the controversial attitude about the extent of surgery (total thyroidectomy plus I131 or individualized surgery) can also negatively influence the risk for recurrence. In our series, eight patients died of thyroid cancer.