Radioiodine Ablation of Remaining Thyroid Lobe in Patients with Differentiated Thyroid Cancer Treated by Lobectomy: A Systematic Review and Metaanalysis

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FIGURE 1.
PRISMA flow diagram.
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FIGURE 2.
Proportion of rate ablation (with 95% confidence interval) of studies included in metaanalysis, with pooled result represented by diamond.
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FIGURE 3.
Metaregression scatterplot showing correlation between ablation rate (log) and radioiodine activity. Each circle represents study in metaanalysis, and size of circle is proportional to sample size.
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FIGURE 4.
Proposed flowchart for ¹³¹I lobar ablation. FNA = fine-needle aspiration; rhTSH = recombinant human thyroid-stimulating hormone; THW = thyroid hormone withdrawal.

TABLE 1

Characteristics of Included Studies

Study	Country	Design	Patients (n)	Selection criteria
Randolph (2002)	United States	Retrospective	50	Thyroid cancer confirmed after lobectomy; no distant metastases
Hoyes (2004)	United Kingdom	Retrospective	60	Thyroid cancer confirmed after lobectomy; no distant metastases
Bal (2006)	India	Prospective	85	DTC confirmed after lobectomy, limited to thyroid gland; negative neck ultrasound
Santra (2011)	India	Retrospective	364	Thyroid cancer confirmed after lobectomy, limited to thyroid gland; negative neck ultrasound
Giovanella (2013)	Switzerland	Randomized and prospective	136	Unifocal DTC confirmed after lobectomy, limited to thyroid gland; negative neck ultrasound

TABLE 2

Patient Characteristics, Therapeutic Protocol, and Ablation Criteria

Study	Age (y)	Histology	T	N	Stage	¹³¹I activity (GBq)	TSH stimulation	TSH at time of ¹³¹I therapy	Ablation criteria for each study
Randolph (2002)	49.5 (mean)	PTC (60%), FTC (28%), HCC (12%)	pT1–pT4	N0 (64%), N1 (36%)	I–IVa	1.1	THW	76 μIU/mL (mean)	NR
Hoyes (2004)	51 (median)	PTC (60%), FTC (23%), HCC (17%)	NR	NR	NR	3.5	THW	NR	Uptake < 1% on ¹³¹I DxWBS
Bal (2006)	37.9 (mean)	PTC (76%), FTC (24%)	NR	N0	NR	1.2 (mean)	THW	11.7 μIU/mL (mean)	Uptake < 0.2% on ¹³¹I DxWBS and Tg < 10 ng/mL
Santra (2011)	38 (mean)	PTC (78%), FTC (20%), HCC (6%)	NR	N0	NR	1.47 (mean)	THW	NR	Uptake < 0.2% on ¹³¹I DxWBS and Tg < 10 ng/mL
Giovanella (2013)	44 (mean)	PTC (57%), follicular thyroid carcinoma (43%)	pT1 and pT2	N0	I–II	1.1 (48%)–3.7 (52%)	THW	>25 μIU/mL in all patients	Negative ¹³¹I DxWBS and stimulated Tg < 2 ng/mL

TSH = thyroid-stimulating hormone; PTC = papillary thyroid carcinoma; FTC = follicular thyroid carcinoma; HCC = hepatocellular carcinoma; THW = thyroid hormone withdrawal; NR = not reported; DxWBS = diagnostic radioiodine whole-body scintigraphy; Tg = thyroglobulin.
American Thyroid Association successful ablation criteria are negative imaging and either suppressed thyroglobulin < 0.2 ng/mL or TSH-stimulated thyroglobulin < 1 ng/mL (1)

TABLE 3

One-Year Response to Initial Therapy (Surgery Plus ¹³¹I) According to 2015 American Thyroid Association Guidelines (1)

Study	Complete response (negative imaging and suppressed Tg < 0.2 ng/mL (1))	Incomplete biochemical response (negative imaging and suppressed Tg > 1 ng/mL (1))	Incomplete structural response (structural or functional evidence of disease with any Tg level (1))
Randolph (2002)	28 (76%)	12 (24%)	0
Hoyes (2004)	49 (82%)	11 (18%)	0
Bal (2006)	NE	NE	NE
Santra (2011)	NE	NE	14 (3.8%)
Giovanella (2013)	51 treated with 1.1 GBq (76%)	16 treated with 1.1 GBq (24%)	0
	65 treated with 3.7 GBq (92%)	4 treated with 3.7 GBq (8%)

TABLE 4

Quality Assessment of Studies and Risk of Bias for Each Study Considered