Table 1.

The various prognostic scoring systems and risk stratification used in the study

Scoring system	Formula	Risk stratification
TNM	T0 = no tumour detected T1 = intrathyroidal tumour <1cm T2 = intrathyroidal tumour 1–4cm T3 = intrathyroidal tumour >4cm T4 = locally invasive tumour of any size T4a = moderately advanced T4b = very advanced N0 = no regional lymph node involvement N1 = regional lymph node metastasis N1a = metastasis to level VI nodes N1b = metastasis to all other cervical nodes M0 = no distant metastasis M1 = distant metastasis	5-year survival  Stage I <45 years: any T, any N, M0 = 100%  Stage I ≥45 years: T1, N0, M0 = 100%  Stage II <45 years: any T, any N, M1 = 100%  Stage II >45 years: T2, N0, M0 = 100%  Stage III: T3, N0, M0 or T1–3, N1a, M0 = 71%  Stage IVA: T1–3, N1b, M0 or T4a, any N, M0 = 50%  Stage IVB: T4b, any N, M0 = 50%  Stage IVC: any T, any N, M1 = 50%
AGES	0.05 x age in years (if age is ≥40 years) or +0 (if age is <40 years) +1 if tumour is grade 2 +3 if tumour is grade 3 or 4 +3 if distant metastases +0.2 x tumour size in cm	20-year survival  ≤3.99 = 99%  4–4.99 = 80%  5–5.99 = 67%  ≥6 = 13%
MACIS	3.1 (if age <40 years) or 0.08 x age in years (if age ≥40 years) +0.3 x tumour size in cm +1 if incompletely resected +1 if locally invasive +3 if distant metastases	20-year survival  <6 = 99%  6–6.99 = 89%  7–7.99 = 56%  ≥8 = 24%
AMES	Low risk: Men ≤40 years or women ≤50 years with no metastases, or older patients with intrathyroidal lesions, minor capsular invasion, tumour size <5cm and no distant metastases High risk: All patients with distant metastases, extrathyroidal lesions or major capsular invasion, or tumour size ≥5cm in older patients	20-year survival  Low risk = 99%  High risk = 61%
EORTC	+12 if male, +10 if follicular lesion is poorly differentiated, +10 if ≥T3, +15 if there is one distant metastasis, +15 for each additional metastasis	5-year survival  <50 = 95%  50–65 = 80%  66–83 = 51%  84–108 = 33%  >108 = 5%

AGES = Age, Grade, Extent, Size; AMES = Age, Metastases, Extent, Sex; EORTC = European Organisation for Research and Treatment of Cancer; TNM = Tumour, Nodes, Metastases; MACIS = Metastases, Age, Completeness of resection, Invasion, Size