Abstract
INTRODUCTION: The risk of recurrent/persistent disease (RD/PD) in differentiated thyroid cancer (DTC) is predicted using American Thyroid Association (ATA) Risk Stratification System (RSS) guidelines - 2009 followed by revision in 2015, which necessitated a more detailed histopathology report which was not available in resource poor settings. A comparative study of the two systems was done to assess the change in risk status and the impact on outcome in a cohort of DTC patients. METHODS: Clinico-pathologic parameters of 221 adults with DTC who had total thyroidectomy with subsequent radioactive iodine ablation were analysed to reassign risk category according to the ATA RSS 2009 and 2015, and the clinical end points were compared between both systems. RESULTS: Among the 127 subjects in the intermediate risk category of ATA RSS-2009, when re-categorised under ATA RSS-2015, only 12 subjects (9.4%) had a change of risk status. Response to therapy at 1 year and final outcome were comparable among the similar risk categories, irrespective of the ATA system used. ATA RSS-2009 and ATA RSS-2015 were comparable in predicting the outcome at final follow-up. CONCLUSION: When risk status was reassigned with ATA RSS-2015, the study showed a shift in the intermediate risk category of ATA RSS-2009, but this was not statistically significant. Moreover, in predicting the outcome, ATA RSS 2015 was similar to ATA RSS-2009. This implies that the ATA RSS-2009 can be used for the initial risk stratification of patients in a resource-poor setting where the availability of complete histopathological data may be lacking.