Long-term outcome of differentiated thyroid carcinoma: experience in a developing country

The presentation and outcome of differentiated thyroid carcinoma (DTC) in developing countries are different from the developed nations. We report the clinicopathologic profile and long-term outcome of DTC in an iodine-deficient area (IDA) in a developing country.

This retrospective study included 302 patients with DTC operated between 1989 and 2002. These patients had been followed up for a minimum period of 5 years after surgery. Clinicopathological profile, intervention, and follow-up details were noted.

Mean age of the patients was 42 +/- 14 years. Mean follow-up period was 80 +/- 34 (24-196) months. Papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), and poorly differentiated thyroid carcinoma (PDTC) was present in 62, 30, and 8% patients, respectively. Mean tumor size was 3.5 cm. Tumor multicentricity was noted in 40% of PTC, 22.2% of FTC, and 25% of PDTC patients. Lymphadenopathy was observed in 45, 10, and 67% patients with PTC, FTC, and PDTC, respectively. Extrathyroidal invasion and distant metastasis were observed in 36.8% (PTC 33%; FTC 36%; PDTC 71%) and 27% (PTC 17%; FTC 44%; PDTC 42%) of cases, respectively. Twenty percent of patients had synchronous metastases. Risk stratification ratio was 1:1.8 (high-risk vs. low-risk). Initial operative procedure was total thyroidectomy in 86.5% cases, and therapeutic lymph node dissection was performed in 37% cases. A total of 77.2% patients received adjuvant radioiodine therapy. Disease recurred in 26.6% of patients (thyroid bed recurrence 1.7%), and 21.2% patients died during follow-up. Overall survival (OS) rate at 10 years in both low-risk and high-risk groups of FTC (80 and 54%) was inferior to PTC (94 and 62%). Five-year OS for PDTC was 50%. Tumor multicentricity was a significant risk factor for OS in the low-risk group, whereas the presence of skeletal metastases and extrathyroidal invasion were significant factors for OS in the high-risk group.

Advance stage at presentation and proportionately high rates of FTC and PDTC contribute to poor outcome of DTC in developing countries. Despite dismal outcome, total thyroidectomy seems to prevent thyroid bed recurrence in surviving patients.