Purpose: the validation of a new scoring model considering the principal risk factors of differentiated thyroid cancer (DTC) relapse.
Methods: we evaluated all DTC patients treated with thyroidectomy and radioactive iodine (RAI) therapy. Three domains were considered: the demographic domain (age and gender), the surgical domain (histology and the American Thyroid Association risk categories), and the RAI-related domain (pre-RAI thyroglobulin and post-therapeutic 131I whole-body scan). The progression-free survival was assessed. The patients' sample was randomly split into a training and validation set. The three-domain score was calculated as the weighted sum of the levels of each significant factor, then scaled to an integer range (0-100) and, finally, stratified into terciles: mild risk 0-33, moderate risk 34-66, and severe risk 67-100.
Results: 907 DTC patients were included. The RAI-related domain was the most relevant factor in the score calculation. The tercile stratification identified significantly different survival curves: patients within the two upper terciles showed approximately 6 to 30 times more progressive risk than patients at mild risk.
Conclusion: we have validated a three-domain scoring system and the principal impact on this score is provided by the peri-RAI findings, whose prognostic role seems to be essential in risk identification.
Keywords: DTC; RAI; domains; post-therapeutic 131-I-WBS; pre-RAI Tg; scoring system.