Table 1. Clinicopathological characteristics of female patients with TC, TC2BC, and BC2TC groups.

Covariate	Level	TC group (n=128,888)			TC2BC group (n=3,000)			BC2TC group (n=2,897)		P value
		Number	%		Number	%		Number	%
Age	<55	90,649	70.33		1,742	58.07		971	33.52	<0.001
	≥55	38,239	29.67		1,258	41.93		1,926	66.48
Race	Black	9,087	7.15		199	6.65		220	7.61	0.685
	White	103,012	81.08		2,448	81.79		2,331	80.63
	Other	14,957	11.77		346	11.56		340	11.76
Year of diagnosis	1974–1994	12,879	9.99		866	28.87		179	6.18	<0.001
	1995–2016	116,009	90.01		2,134	71.13		2,718	93.82
Grade	I	19,754	15.33		407	13.57		427	14.74	<0.001
	II	4,580	3.55		128	4.27		99	3.42
	III	1,351	1.05		26	0.87		38	1.31
	IV	1,610	1.25		7	0.23		52	1.79
	Unknown	101,593	78.82		2,432	81.07		2,281	78.74
Histology	Papillary carcinoma	112,849	93.49		2,552	90.56		2,490	93.96	<0.001
	Follicular carcinoma	7,855	6.51		266	9.44		160	6.04
T-stage	T1	29,152	22.62		285	9.50		789	27.24	0.015
	T2	7,915	6.14		60	2.00		172	5.94
	T3	8,798	6.83		71	2.37		235	8.11
	T4	1,525	1.18		15	0.50		54	1.86
	Unknown	81,498	63.23		2,569	85.63		1,647	56.85
N-stage	N0	37,437	29.05		375	12.50		1,044	36.04	<0.001
	N1	10,427	8.09		63	2.10		224	7.73
	Unknown	81,024	62.86		2,562	85.40		1,629	56.23
M-stage	M0	48,490	37.62		438	14.60		1,284	44.32	0.677
	M1	754	0.59		7	0.23		24	0.83
	Unknown	79,644	61.79		2,555	85.17		1,589	54.85
Multifocality	Solitary tumor	54,879	42.58		736	24.53		1,477	50.98	0.03
	Multifocal tumor	34,521	26.78		494	16.47		837	28.89
	Unknown	39,488	30.64		1,770	59.00		583	20.12
Extension	Yes	69,682	54.06		1,065	35.50		1,741	60.10	0.087
	No	12,326	9.56		175	5.83		347	11.98
	Unknown	46,880	36.37		1,760	58.67		809	27.93
Radiation	Refused	414	0.32		8	0.27		5	0.17	0.529
	Yes	57,203	44.38		1,257	41.90		1,117	38.56
	Unknown	71,271	55.30		1,735	57.83		1,775	61.27
Surgery	No	4,738	3.70		59	1.97		213	7.41	<0.001
	Yes	123,342	96.30		2,932	98.03		2,663	92.59
Survival months	–	22.00 (13.00–49.00)			155.00 (95.00–241.75)			57.50 (24.00–104.00)		<0.001
CSS	Alive	124,982	96.97		2,961	98.70		2,800	96.70	<0.001
	Death	3,906	3.03		39	1.30		97	3.35
OS	Alive	117,501	91.17		2,314	77.13		2,278	78.63	<0.001
	Death	11,387	8.83		686	22.87		619	21.37

TC, thyroid cancer; BC, breast cancer; TC2BC, BC after TC; BC2TC, BC before TC; CSS, cancer-specific survival; OS, overall survival.