Changes in clinical presentation, management and outcome in 1348 patients with differentiated thyroid carcinoma: Experience in a single institute in Hong Kong, 1960-2000

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=3.5 cm: 2.8 cm: 2.5 cm). with a greater percentage of microcarcinoma of I cm 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 (I-131, 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.