OBJECTIVE. To study the clinical parameters and treatment outcome of medullary thyroid carcinoma in Hong Kong Chinese patients.

DESIGN. Retrospective study.

SETTING. Regional oncology unit, Hong Kong.

PATIENTS. Patients with medullary thyroid carcinoma who were identified among 1656 patients with thyroid malignancies seen in a single institute in Hong Kong from January 1960 to June 2003.

MAIN OUTCOME MEASURES. Ten-year cause-specific survival, locoregional failure-free survival, and distant metastasis failure-free survival.

RESULTS. Twenty-two (1.3%) patients with medullary thyroid carcinoma were identified. The mean age at diagnosis was 43.7 (standard deviation, 16.5) years. The sex ratio was 1:1. The 10-year cause-specific survival, locoregional failure-free survival, and distant metastasis failure-free survival were 75.4%, 82.0%, and 62.4%, respectively. Lymph node metastasis was present in seven (31.8%) patients at diagnosis. Distant metastasis developed in nine (40.9%) patients: lung, 3 (13.6%); bone, 5 (22.7%); liver, 2 (9.1%); mediastinum, 4 (18.2%). Seven (31.8%) patients died of distant metastasis. Mediastinal (n=3) and bone metastases (n=3) were important causes of death. Genetic study confirmed multiple endocrine neoplasia type 2A in 3 (25.0%) of 12 patients who all had bilateral and multifocal diseases. Younger age (