THE BELGIAN THYROID-CANCER STUDY-GROUP, P RELIMINARY EPIDEMIOLOGIC TRENDS REVEALED BY A RETROSPECTIVE ANALYSIS (1988-1995)

The aim of a cancer registry is to study the incidence of cancer in a well-determined population and to allow epidemiological research to th e setting up of diagnosis and therapeutic strategies. The Belgian Thyr oid Cancer Study Group (BTCSG) was founded in 1990. In the present stu dy we report data collected from 1988 to 1995 in 397 patients with a d ifferentiated (papillary and follicular) thyroid carcinoma living in t he french-speaking area of Eel gium-. The sex ratio female/male is 3.5 and the median ages at the diagnosis, is similar (45 yrs, 12-82) in b oth sexes. Seven cases of thyroid cancer were registred in young patie nts less than 18 yrs old. Thyroid cat-cinema were associated with mult inodular goiter in more than 50% cases. Cancer was bilateral in 17%. P apillary histological type accounts for 84% in our series while its di agnosis was established in 45% at early clinical stages (TO-T1). These observations could probably be related with I) broader indications an d more agressive options for the surgical removal of diffuse multimodu lar goiter, 2) more sophisticated pathologic examinations that might h ave led to the detection of a greater incidence of occult carcinomas, incidentally discovered. Lymph nodes metastases were present at the ti me of diagnosis in 20%, especially in young patients. The risk for loc al and/or lateral recurrence or distant metastases is significantly re lated to the size of the tumor, histologically verified lymph node met astases and the values of the EORTC prognotic index (greater than or e qual to 50) that additionnally takes into account the differentiation of the tumor. Considering our short median follow-lip ri,ne of 25 mont hs, it is currently too early to define if the controversial attitude about the extent of surgery (total thyroidectomy plus 1131 or individu alized surgery) can also negatively influence the risk for recurrence. bz our series, eight patients died of thyroid cancer.