Optimal thyrotropin level for low-risk papillary thyroid carcinoma after ultrasound-guided radiofrequency ablation

Figures & data

Figure 1. Flowchart of patient selection. PTC: papillary thyroid carcinoma; RFA: radiofrequency ablation; TSH: thyroid stimulating hormone.

Table 1. Baseline characteristics of low-risk PTC patients who underwent radiofrequency ablation with TSH suppressive therapy.

Characteristic	Total (n = 516)	Before propensity score matching			After propensity score matching
		Low TSH (n = 463)	High TSH (n = 53)	p Value	Low TSH (n = 106)	High TSH (n = 53)	p Value
Age, years (%)				0.726			0.377
≤55	460(89)	412(89)	48(91)		100(94)	48(91)
>55	56(11)	51(11)	5(9)		6(6)	5(9)
Sex, No. (%)				0.008*			1.000
Male	112(22)	108(23)	4(8)		8(8)	4(8)
Female	404(78)	355(77)	49(92)		98(92)	49(92)
Tumor size, No. (%)				0.693			0.248
≤1 cm	459(89)	411(89)	48(91)		101(95)	48(91)
1–≤2 cm	57(11)	52(11)	5(9)		5(5)	5(9)
Location				0.308			0.288
Left lobe	216(42)	190(41)	26(49)		44(42)	26(49)
Isthmus	12(2)	12(3)	0(0)		3(3)	0(0)
Right lobe	288(56)	261(56)	27(51)		59(55)	27(51)
Thyroid function				0.448			0.531
CLT	106(21)	93(20)	13(25)		31(29)	13(25)
Normal	410(79)	370(80)	40(75)		75(71)	40(75)
BRAF^V600E mutation				0.214			0.564
Positive	337(65)	306(66)	31(58)		67(63)	31(58)
Negative	179(35)	157(34)	22(42)		39(37)	22(42)
Greatest diameter, mm	7.0(3.1)	7.1(3.1)	6.4(2.8)	0.080	5.9(2.4)	6.4(2.8)	0.269
Volume, mm^3	90.2(147.3)	92.1(156.8)	73.6(89.7)	0.196	42.1(122.0)	73.6(89.7)	0.123
Follow-up time, months	59.3(15.5)	59.8(15.4)	54.6(15.4)	0.012*	56.2(15.6)	54.6(15.4)	0.418

Categorical variables were described by numbers with percentages and continuous variables were described by mean±SD or median (IQR).

CLT: chronic lymphocytic thyroiditis.

*p < 0.05 was considered statistically significant.

Table 2. The comparison of local tumor progression between the two groups.

Characteristic	Total (n = 516)	Before propensity score matching		After propensity score matching
		Low TSH (n = 463)	High TSH (n = 53)	Low TSH (n = 106)	High TSH (n = 53)
Total incidence	25(4.8)	20(4.3)	5(9.4)	7(6.6)	5(9.4)
LNM	4(0.8)	3(0.6)	1(1.9)	0	1(1.9)
Developed time, months	18.0(7.0)	17.3(8.4)	73.6	–	73.6
Greatest diameter, mm	8.5(1.3)	9.0(1.0)	7	–	7
Developed volume, mm^3	99.9(30.2)	103.4(8.0)	20	–	20
Location, lateral: cervical		1:3	0:1	0:0	0:1
Newly found PTC	16(3.1)	12(2.6)	4(7.5)	6(5.7)	4(7.5)
Developed time, months	28.8(14.9)	29.3(16.1)	27.0(12.7)	26.5(19.5)	27.0(12.7)
Greatest diameter, mm	5.1(2.3)	5.6(3.0)	3.8(1.5)	6.5(3.8)	3.8(1.5)
Developed volume, mm^3	32.2(79.3)	46.0(75.7)	9.5(52.1)	67.1(224.1)	9.5(52.1)
Location, psilateral: contralateral		9:5	2:2	5:2	2:2
Persistent lesions	5(0.9)	5(1.1)	0	1(0.9)	0

Categorical variables were described by numbers with percentages and continuous variables were described by mean±SD or median (IQR).

LNM: lymph node metastases; PTC: papillary thyroid carcinomas.

Figure 2. Disease-free survival curves for low vs. high TSH levels in low-risk PTC after RFA. TSH: thyroid stimulating hormone; PTC: papillary thyroid carcinoma; RFA: radiofrequency ablation.

Table 3. Analysis of hazard ratios of local tumor progression in cox proportional hazards regression models.

Characteristic	Before propensity score matching		After propensity score matching
	Univariate analysis		Univariate analysis
Variable	HR (95% CI)	p Value	HR (95% CI)	p Value
Age, years (%)
≤55	2.99(0.40,22.07)	0.284	0.77(0.10,5.97)	0.802
>55
Sex, No.(%)
Male	0.49(0.15,1.62)	0.240	0.04(0.00,519.17)	0.985
Female
Tumor size, No.(%)
≤1 cm	0.24(0.10,0.56)	0.010*	0.11(0.03,0.38)	0.000*
1–≤2 cm
Thyroid function
CLT	0.38(0.17,0.85)	0.019	0.82(0.25,2.72)	0.74
Normal
BRAF^V600E mutation
Positive	0.85(0.37,1.97)	0.705	1.09(0.35,3.44)	0.881
Negative
TSH
Low (≤ 2 mIU/L)	0.44(0.16,1.17)	0.098	0.67(0.21,2.13)	0.504
High (> 2 mIU/L)

CLT: chronic lymphocytic thyroiditis; HR: hazard ratio; CI: confidence intervals.

*p < 0.05 was considered statistically significant.