Table 1 Characteristics of the included studies

Mäenpää 2008 [19]

Finland (monocentric)

160

P / F

T?, any N, M0 (“patients with macroscopic inoperable locoregional disease were excluded”)

TT or NT

1.1 (n = 81) vs

3.7 (n = 79*) after WD (randomization: stratified according to the presence or absence of histologically verified cervical lymph node metastases)

Median 4.25 (51 months)

(18–77 m)

4–8 months after RIT:

1) absence of abnormal uptake in a diagnostic whole body 131-I scan (185 MBq after WD),

2) Tg < 1 ng/mL) during both levothyroxine administration and TSH stimulation (WD or rhTSH),

3) absence of palpable metastases in the neck (neck US not mandated).

All three conditions had to be met for ablation to be considered as successful.

SA; metastatic cervical lymph nodes were removed (=histology?); the 1.1 GBq group, n = 6; the 3.7 GBq group, n = 6. Three patients in the 3.7 GBq group and none in the 1.1 GBq group were diagnosed with distant metastases (Histology?) (P = 0.12). None died from thyroid cancer during follow-up.

Kukulska 2010 [20]

Poland (monocentric)

181 (86 + 95)

P / F

T ≥ 1b or Tx, any N, M0

(only patients with no evidence of persistent disease after TT and appropriate lymph node dissection)

TT (and in most cases lymph node dissect.)

1.1 (n = 86) vs

2.2 (n = 128) vs

3.7 (n = 95)

(30 mCi vs 60 mCi vs 100 mCi) after WD

Median 10 (2–12)

12 months after RIT (after WD):

1) absence of thyroid bed uptake in 131-I neck scan,

2) stimulated Tg < 10 ng/mL.

All two conditions had to be met for ablation to be considered as successful.

follow up; ultrasonography and radiological examinations and serum Tg level (on LT4-suppressive treatment), Histology not available

Schlumberger 2018 [21]

France (polycentric, 24 centers)

726

P / F

(excluding aggressive histological subtypes)

T1 ≤ 1 cm with N1 or Nx,

T1 > 1 cm with any N,

T2 with N0,

always M0

TT

1.1 (n = 363) vs

3.7 (n = 363)

359 after WD, 367 rhTSH (randomized)

Median 5.4 (0.5–9.2)

6–10 months after RIT (after rhTSH):

1) normal result on neck US and

2) Tg ≤ 1.0 ng/mL after stimulation (or a normal diagnostic iodine total-body san with 148-185 MBq (4-5 mCi) in patients with serum thyroglobulin antibodies)

follow up; Tg > 1 ng/mL on levothyroxine treatment was considered abnormal. Structural abnormalities on neck US were confirmed by FNA. No evidence of disease was defined as serum Tg ≤1 ng/mL on levothyroxine treatment and normal results on neck US when performed, but TSH stimulated serum thyroglobulin was not taken into account in this classification; Histology not available

Dehbi 2019 [3]

UK (polycentric, 29 centers)

434

DTC, no aggressive malignant variants

T1–3, any N, M0

TT or NT (with or without lymph node dissect.)

1.1 (n = 217) vs

3.7 (n = 217)

216 after WD, 218 rhTSH (randomized)

Median 6.5 y

78.4 months)

(0.3–127 m)

6–9 months after RIT:

serum Tg < 2.0 ng/mL and scan uptake < 0.1% (neck US not routinely used).

follow-up at annual clinical visits. Methods used to diagnose recurrence: serum Tg, neck US, diagnostic radioactive iodine scan, PET-scan, MRI scan; FNA (in some patients)