Recombinant Human TSH–Assisted Radioactive Iodine Remnant Ablation Achieves Short-Term Clinical Recurrence Rates Similar to Those of Traditional Thyroid Hormone Withdrawal

R. Michael Tuttle; Matvey Brokhin; Gal Omry; Andrew J. Martorella; Steven M. Larson; Ravinder K. Grewal; Martin Fleisher; Richard J. Robbins

doi:10.2967/jnumed.107.049072

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FIGURE 1.
Study time line.
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FIGURE 2.
Kaplan–Meier curve showing time to recurrence in both rhTSH cohort and THW cohort. Longer time of follow-up for THW did not result in higher recurrence rates, because most recurrences in both groups were detected in first 24–36 mo after ablation.

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TABLE 1

Patient and Tumor Characteristics

Characteristic	THW (n = 74)	rhTSH (n = 320)	P
Mean age (±SD) at diagnosis (y)	44.0 ± 15.0	48.3 ± 15.0	0.03
Sex (%)
Female	67.6	72.2	0.43
Male	32.4	27.8
Cancer histology (%)
Papillary	58.1	65.6	0.14
Follicular	1.4	2.2
Follicular variant of papillary	39.2	26.3
Hurthle	1.4	3.8
Poorly differentiated	—	2.2
TNM classification (%)
TX	1.4	—	0.06
T1	37.8	26.3
T2	21.6	19.7
T3	33.8	45.9
T4a	5.4	6.6
T4b	—	1.6
NX	—	0.3	0.50
N0	58.1	48.8
N1a	17.6	23.1
N1b	24.3	27.8
M0	93.2	94.4	0.71
M1	6.8	5.6
Disease stage (AJCC6)
I	59.5	52.8	0.85
II	6.8	8.1
III	17.6	21.6
IVa	12.2	13.4
IVb	—	0.9
IVc	4.1	3.1

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TABLE 2

Nuclear Medicine Parameters and Follow-up Time

Parameter	THW (n = 74)	rhTSH (n = 320)	P
¹³¹I dose (MBq)
Median	3,811	4,033	0.01
Mean ± SD	4,179 ± 2,220	4,800 ± 1,739
Range	1,073–13,616	1,110–15,170
¹³¹I dose (mCi)
Median	103	109	0.01
Mean ± SD	113.0 ± 60.1	129.7 ± 46.7
Range	29–368	30–410
Follow-up time (mo)
Median	45	27	<0.001
Mean ± SD	47.1 ± 23.8	31.0 ± 15.1
Range	12–111	9–78
Time to recurrence (mo)
Median	16	17	0.86
Mean ± SD	19.6 ± 15.8	18.5 ± 9.0
Range	8–47	10–40

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TABLE 3

Thyroid Bed Uptake on Follow-up DxWBS

Parameter	Negative 48-h TB uptake	48-h TB uptake of 0%–0.1%	48-h TB uptake ≥ 0.1%	P
THW (n = 71)	76.0% (54)	14.1% (10)	9.9% (7)	0.35
rhTSH (n = 220)	82.7% (182)	11.8% (26)	5.5% (12)
Total (n = 291)	81.1% (236)	12.4% (36)	6.5% (19)

TB = thyroid bed.

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TABLE 4

Serum Thyroglobulin at Follow-up

Parameter	THW	rhTSH	P
Suppressed thyroglobulin (ng/mL)
6 mo
Median	1.0	0.6	0.003
Mean ± SD	44.2 ± 213.9	5.0 ± 27.5
Range	0–1,296	0–288
12–18 mo
Median	0.8	0.6	0.62
Mean ± SD	4.9 ± 13.7	138.4 ± 2299.5
Range	0–78	0–40,800
Stimulated thyroglobulin (ng/mL)
12–18 mo
Median	1.0	0.8	0.59
Mean ± SD	26.2 ± 119.1	272.3 ± 3,648.5
Range	0–900	0–56,000
Suppressed thyroglobulin (ng/mL) at final follow-up
Median	0.6	0.6	0.61
Mean ± SD	44.4 ± 328.7	2060.1 ± 33736.7
Range	0–2,800	0–598,000

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TABLE 5

Clinical Outcomes a Median of 2.5 Years After Initial Ablation Using Suppressed Thyroglobulin of Less Than 2 ng/mL and Stimulated Thyroglobulin of Less Than 10 ng/mL to Define NCED

Parameter	NCED	Clinical recurrence	Persistent disease	TB uptake Only	P
THW (n = 74)	62.2% (46)	6.8% (5)	24.3% (18)	6.8% (5)	0.10
rhTSH (n = 320)	76.3% (244)	3.8% (12)	15.9% (51)	4.1% (13)
Total (n = 394)	73.6% (290)	4.3% (17)	17.5% (69)	4.6% (18)

TB = thyroid bed.

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TABLE 6

Clinical Outcomes a Median of 2.5 Years After Initial Ablation Using Suppressed Thyroglobulin of Less Than 1 ng/mL and Stimulated Thyroglobulin of Less Than 2 ng/mL to Define NCED

Parameter	NCED	Clinical recurrence	Persistent disease	TB uptake Only	P
THW (n = 74)	55.4% (41)	6.8% (5)	32.4% (24)	5.4% (4)	0.021
rhTSH (n = 320)	73.8% (236)	3.8% (12)	19.4% (62)	3.1% (10)
Total (n = 394)	70.3% (277)	4.3% (17)	21.8% (86)	3.6% (14)

TB = thyroid bed.

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TABLE 7

Clinical Outcomes, Based on Initial Risk Stratification, a Median of 2.5 Years After Initial Ablation Using Suppressed Thyroglobulin of Less Than 1 ng/mL and Stimulated Thyroglobulin of Less Than 2 ng/mL to Define NCED

Parameter	NCED	Clinical recurrence	Persistent disease	TB uptake only	P
Excluding distant metastases at diagnosis (M1)
THW (n = 69)	73% (50)	6% (4)	17% (12)	4% (3)	NS
rhTSH (n = 302)	82% (246)	4% (12)	11% (32)	4% (12)
Total (n = 394)	80% (296)	4% (16)	12% (44)	4% (15)
AJCC6 I and II without distant metastases
THW (n = 49)	78% (38)	2% (1)	16% (8)	4% (2)	NS
rhTSH (n = 195)	84% (163)	2% (4)	11% (22)	3% (6)
Total (n = 244)	82% (201)	2% (5)	12% (30)	3% (8)