Changes in Clinical Presentation, Management and Outcome in 1348 Patients with Differentiated Thyroid Carcinoma: Experience in a Single Institute in Hong Kong, 1960–2000

Abstract The clinical features, management and outcome of 1348 patients diagnosed with differentiated thyroid carcinoma in Queen Elizabeth Hospital, Hong Kong, were analysed according to the period of diagnosis: A (before 1980), B (1981–1990) and C (1991–2000). As time advanced, ratio of papillary carcinoma (PTC) to follicular carcinoma (FTC) increased (A:B:C=1.6: 3.1: 7.2). The mean size of the primary tumour decreased (A:B:C=3.5cm: 2.8cm: 2.5cm), with a greater percentage of microcarcinoma of 1cm or less (A:B:C=5.1%: 16.1%: 21.7%). At presentation, the incidence of lymph-node metastasis decreased (A:B:C=32.7%: 31.6%: 24.8%) and that of distant metastasis decreased (A:B:C=9%: 6.1%: 5.3%). Bilateral surgical resection was more commonly used (A:B:C=62.8%: 89.1%: 94.8%) than lobectomy (A:B:C=26.3%: 2.8%: 1.8%). Radiation treatment, radioactive iodine ( 131 I; RAI) and external radiotherapy (EXT), was more commonly used (A:B:C=53.2%: 74.7%: 85.1%). RAI was used in 84.3% (A:B:C=50%: 71.2%: 84.3%) and EXT in 14.5% of patients in the past decade (A:B:C=10.9%: 8.7%: 14.5%). The proportion of patients who adopted a bilateral surgery and RAI treatment increased gradually with time (A:B:C=33%: 68%: 83.8%). The 5-year cause-specific survival (A:B:C=90.2%: 93.7%: 95.7%), locoregional failure-free survival (A:B:C=72.6%: 82.9%: 91.6%) and distant metastasis failure-free survival (A:B:C=84.5%: 89.1%: 92.6%) were improved. However, the period of diagnosis was not found to be an important explanatory variable (i.e. P >0.05) in Cox regression after adjusting for other factors, indicating that the improvement was probably related to the temporal trend of other factors: presentation at earlier stage, increased ratio of PTC:FTC and more aggressive management by bilateral surgery and radiation therapy.