Table 2.

Definition of disease progression.

Definition of progression of papillary thyroid cancer under active surveillance for which salvage surgery is advised (one or more of the criteria listed below)*
1. Primary index PTC growth >3 mm (in the largest dimension), confirmed on two consecutive ultrasound exams. The 3 mm size cut off is considered reproducible (21)
2. Primary PTC growth in a location that is concerning (e.g. immediately adjacent to the trachea or in the course of the recurrent laryngeal nerve) (22)
3. Incident development of metastatic PTC to lymph nodes (confirmed on cytology or unequivocal imaging)
4. Incident development of distant metastatic PTC (confirmed on imaging or biopsy or surgical histology)

*Patients may choose to have surgery in absence of disease progression at any time point in follow-up.