Outcome definitions
For each simulated case in the model, six possible outcomes were included: (1) under AS; (2) post-surgery with long-term complications; (3) Post-surgery without complications; (4) Cancer recurrence, defined as tumor recurrence or any appearance of new lymph nodes metastasis; (5) Cure, defined as no progression and no complication or recurrence in the surgery group after 20 years of follow-up; and (6) Death. The outcomes prevalence within each strategy were driven from previous literature2,10,14 and are presented in Table 1.
For the AS strategy, patients were defined as ’treatment failure’ in cases of ≥ 3 mm increase in the size of the primary tumor or any new loco-regional metastasis was found, including involvement of cervical lymph nodes. Failure cases were assigned for hemithyroidectomy.