EARLY THERAPEUTIC MANAGEMENT OF SUBJECTS GENETICALLY PREDISPOSED TO MEDULLARY-THYROID CANCER

Study: The aim of our study was to study therapeutic results after thy roidectomy in patients positive for predictive genetic analysis and wi th preoperative calcitonin (CT) response to pentagastlin (Pg) < 150 pg /ml. Material and methods. 36 patients (13 F, 23 M) were selected: 13 F-MTC from 8 families, 22 MEN 2A from 15 families and 1 MEN 2B. They w ere positive for direct RET mutation analysis. CT was assayed by immun oradiometric method before and after Pg. Pg test results before and af ter thyroidectomy, age at operation and histologic results were analys ed. Results. mean preoperative peak CT was 82.5 +/- 34.0 pg/ml (22-133 ); among these 36 patients preoperative basal and peak CT were normal in 16 and 2 patients respectively. F-MTC and MEN 2A patients were diff erent according to their preoperative peak CT levels (58.1 +/- 24.0 vs 97.6 +/- 31.3 pg/ml, p < 0.01) and age at thyroidectomy (20.4 +/- 10. 5 vs 11.6 +/- 7.6 years, p < 0.01 by Mann-Whitney test). Total thyroid ectomy was performed in all patients at a mean age of 14.8 +/- 9.8 yea rs (2.5-41.7) and was associated with lymph node dissection in 30 case s. The 2 F-MTC patients with normal preoperative peak CT levels had bi lateral C-cell hyperplasia (CCH) associated with uni or bilateral micr o-MTC. Other patients had uni or bilateral micro MTC except 4 who had isolated CCH without carcinoma. The age of two MEN-2A and 1 MEN 2B pat ients with micro-MTC ranged from 2.5 to 4.7 yr. Micro MTC was present in 100% of MEN-2A cases after the age of 10 yr. There were no lymph no des metastases. During postoperative survey, the last PG tests (n = 33 ) were performed 27.5 months (1-92) after thyroidectomy: peak CT value s were always < 10 pg/ml. In conclusion: thyroidectomy should be perfo rmed at a very young age in RET mutation carriers, regardless of the p lasma CT values. This choice is justified in NEM-2A and NEM-2B patient s but must be discussed in F-MTC families with less aggressive forms o f the disease.