Prognostic factors in metastatic well differentiated thyroid cancer
Abstract
Well differentiated thyroid cancer is one of the least morbid solid malignancies, with favorable long term survival. However, presence of distant metastases at time of initial evaluation (synchronous metastases, SM) is a strong predictor of poor outcome, as 43-90% of those patients die from their thyroid malignancy.
The aim of the current study is to detect significant prognostic factors that can affect patient outcome and disease specific survival in patients with well differentiated thyroid cancer associated with SM.
Patients and methods: retrospective analysis of data from patients with pathologically proven well differentiated thyroid cancer having established SM was done. All patients were presented to three oncology centers in the period from Jan. 1992 to Jan 2007. 101 patients were included in the current study, they were followed up for a mean period of 60months, evaluating the effects of different factors on patient outcome and survival.
Results: It was found that age, size and extent of metastases and their ability to accumulate I131 had positive impact on patient outcome and survival .Young patients with few small metastatic lesions that have the ability to accumulate radioactive iodine (I131) have significantly better outcome and survival compared to those older than 45 years, with multiple big metastases that do not accumulate I131. On the other hand, gender, type of histopathology, local recurrence, the site of metastases and serum thyroglobulin(Tg) level have no statistical significant difference on patient outcome and survival.
Conclusion: In patients with well differentiated thyroid cancer associated with SM the most important factors that have significant impact on patient outcome and do affect survival are age, size, extent of metastatic lesions, as well as, their ability to accumulate I131. The most favorable outcome is for patients younger than 45 years with few small SM that accumulate I131.