LATENT SUBCLINICAL MEDULLARY-THYROID CARCINOMA - DIAGNOSIS AND TREATMENT

Sporadic medullary thyroid carcinoma (SMTC) is usually diagnosed at a clinical stage often associated with lymph node involvement. Hence sur gical treatment does not result in definitive cure in many patients. S tudies have demonstrated that routine measurement of serum basal calci tonin (CT) in patients with nodular thyroid disease allows preoperativ e, early diagnosis of unsuspected SMTC. The aim of this work was to as sess the results of surgery in patients operated on For subclinical SM TC detected preoperatively by measurement of serum CT. Results were co mpared with those obtained in patients with SMTCs diagnosed at a clini cal stage and operated on during the same period. During a 4-year peri od (1993-1996) 24 SMTCs were diagnosed and treated in our department. They were diagnosed at a clinical stage in 13 patients (group 1): palp able thyroid tumor (n = II), palpable metastatic lymph node (n = 6), d istant metastases (n = 4). In nine eases the diagnosis was made by bot h fine-needle aspiration cytology and serum CT measurement. In the fou r other cases the initial cytology was incorrect, but the diagnosis na s revised on the basis of elevated basal CT values. In ii patients (gr oup 2) presenting with nodular thyroid disease, SMTC was not clinicall y detectable. SMTC was preoperatively suspected by elevated CT levels: basal CT > 10 pg/ml and pentagastrin-stimulated CT peak > 100 pg/ml. One patient in group 1 with distant metastases was not operated on. Al l of the other 12 patients underwent total thyroidectomy and extensive lymph node dissection. The mean size of the tumors was 27 mm. Lymph n ode involvement was found in nine patients. After surgery, CT levels r eturned to normal in five patients hut remained elevated in five other s; the two remaining patients died of distant metastases. All II patie nts in group 2 underwent total thyroidectomy and central neck dissecti on. None of the 11 patients had nodal extension. All 11 patients are b iochemically cured. It was concluded that routine measurement of basal serum CT in those with nodular thyroid disease allows early preoperat ive diagnosis of subclinical SMTC anal improves the results or surgery .