Medullary Thyroid Carcinoma: 25-year Experience and the Results of the RET Proto-oncogene Screening Test

Jeong, Jong Ju; Lee, Yong Sang; Kang, Sang Wook; Sung, Tae Yon; Lee, Seung Chul; Nam, Kee Hyun; Chang, Hang Seok; Chung, Woong Youn; Park, Cheong Soo

Abstract

PURPOSE
Medullary thyroid carcinoma (MTC) is a rare thyroid tumor and its clinical course is quite variable. The aim of this study was to retrospectively analyze our clinical and laboratory data for 25 years to review the clinicopathologic characteristics, the operation methods, the tumor recurrence and the prognosis of medullary thyroid carcinoma. We also reevaluate the limits of the previous diagnostic and treatment modalities. The positivity for and the location of the RET mutation are also evaluated. Finally, we want to contribute to a systemic approach for the diagnosis, treatment, patient management and clinical study of medullary thyroid carcinoma.
METHODS
We conducted a retrospective review of the records of 77 patients with MTC that were seen at our hospital from 1982 to 2007. The medical records were reviewed for the demographic data, the laboratory data and the clinical course, the treatment, the long-term outcome and the RET proto-oncogene mutation. The mean follow-up period was 69.6 months (range: 6~201).
RESULTS
There were 50 females and 27 males. The mean patient age was 44.2 years (range: 1~80). There were 16 cases of the sporadic form (79.2%) and 16 cases of the hereditary form. At diagnosis, 73 patients (94.8%) had local disease and 4 patients (5.2%) had distant metastasis. The patients with the hereditary form were younger than the patients with the sporadic form (P=0.004), and they had more muticentric (P=0.002) and bilateral tumor (P<0.001). The initial surgery consisted of total thyroidectomy in 74 patients (96.1%), and lateral neck dissection in 41 patients (53.2%) (therapeutic: 23, prophylactic: 18), except for 3 cases with less than total thyroidectomy. Forty-four patients (57.1%) achieved a long-term remission state, 13 patients (16.9%) had biochemical persistent disease, and 20 patients (26.0%) had metastasis. The 5- and 10-year survival rates were 86.5% and 74.1% respectively. On univariate analysis, tumor size (more than 2 cm), extracapsular invasion, involvement of the neck nodes and distant metastasis at the time of diagnosis were the significant prognostic factors of persistent or recurrence disease.
CONCLUSION
Patients with MTC generally have a favorable outcome. The presence of distant metastasis at the time of diagnosis is predictive of persistent or recurrence disease by multivariate analysis. In order to achieve an early diagnosis and administer prompt treatment, we suggest that optimal RET oncogene screening and counseling should be performed for medullary patients and their relatives.