High versus low radioiodine activity in patients with differentiated thyroid cancer: A meta-analysis

Figures & data

Figure 1. Flow chart diagram of study selection.

Table I. Characteristics of eligible trials.

Author [ref]	Year	Extent of thyroidectomy	Timing from operation to ablation	Timing from ablation to diagnostic scan	Method for TSH stimulation	Definition of successful ablation	Low-iodine diet	Total no. of patients	Ablation activities (MBq)
Creutzig [12]	1987	Total	3 weeks	3 months	Withdrawal	Neck uptake </ = 0.5%	NR	20	1100 vs. 3700
Johansen [13]	1991	Total and subtotal	1.5 month (median)	NR	Withdrawal and rec-hTSH	Negative WBS and thyroglobulin < 5 μg/l	No	63	1100 vs. 3700
Bal [14]	1996	Total and subtotal	NR	6–12 months	Withdrawal	Negative WBS, neck uptake < 0.2%, thyroglobulin < 10 ng/ml	NR	119	1100 vs. 1850 vs. 3330 vs. 5735 ^a
Gawkowska-Suwinska [15]	2001	Total	NR	6–8	Withdrawal	Negative neck scan and thyroglobulin < 4 ng/ml	NR	98	1100 vs. 2220
Bal [16]	2004	Total and subtotal	2 months (median)	6	Withdrawal	Negative WBS, neck uptake < 0.2%, thyroglobulin < 10 ng/ml^b	No	509	555 vs. 740 vs. 925 vs. 1100 vs. 1295 vs. 1480 vs. 1665 vs. 1850
Mäenpää [17]	2008	Total or near total	5–6 weeks	4–8 months	Withdrawal	Negative WBS and thyroglobulin < 1 ng/ml	Yes	158	1100 vs. 3700
Fallahi [19]	2012	Total or near total	4–6 weeks	6–7 months	Withdrawal	Negative WBS and thyroglobulin < 2 ng/ml	Yes	341	1100 vs. 3700
Mallick [20]	2012	Total and near total	1–6 months	6–9 months	Withdrawal and rec-hTSH	Negative WBS and thyroglobulin < 2 ng/ml	Yes	438	1100 vs. 3700
Schlumberger [21]	2012	Total	NR	8 ± 2 months	Withdrawal and rec-hTSH	Negative WBS and negative neck ultrasound and thyroglobulin < 1 ng/ml	NR	752	1100 vs. 3700

no, number; NR, not-reported; MBq, megabecquerel; rec-hTSH, recombinant human thyroid-stimulating hormone; TSH, thyroid-stimulating hormone; WBS, whole-body scan.

^a The ablation activities of 1100, 1850, 3300, and 5735 are the mean levels from four groups: 25–34, 35–64, 65–119, and 120–200 mCi; ^b Two of three criteria were required.

Figure 2. Forest plot of risk ratio for successful ablation: 1100 MBq versus 3700 MBq. Two trials [21,22] were randomized to not only high versus low dose but also rec-hTSH versus withdrawal for TSH-stimulation. Schlumberger 2012a and Mallick 2012a presented data when rec-hTSH was used while Schlumberger 2012b and Mallick 2012b when withdrawal was used.

Table II. Meta-analysis of early adverse events related to radioiodine ablation.

Adverse events	1100 MBq (n/N)	3700 MBq (n/N)	No. of studies included	RR (95% CI)	p-value
Salivary dysfunction^a	56/653	79/649	3	0.71 (0.52–0.97)	0.03
Nausea	19/288	63/285	2	0.30 (0.19–0.48)	<0.001
Neck pain	36/288	62/285	2	0.57 (0.40–0.82)	0.003
Lacrimal dysfunction^b	58/433	72/431	2	0.81 (0.59–1.10)	0.18
SAEs^c	5/585	6/582	2	0.88 (0.05–16–72)	0.93

n, number of events; N, total number of patients; RR, risk ratio; SAEs, serious adverse events.

^aSalivary dysfunction also includes pain in salivary glands, sialadenitis or other salivary dysfunction; ^bLacrimal dysfunction includes dry eyes as well; ^cThe serious adverse events were not thought from the primary investigators to be related to trial´s interventions.

Figure 3. Forest plot of risk ratio for successful ablation: 1100 MBq versus 1850 MBq.

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