Comparison of Empiric Versus Whole-Body/-Blood Clearance Dosimetry–Based Approach to Radioactive Iodine Treatment in Patients with Metastases from Differentiated Thyroid Cancer

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FIGURE 1.
OS estimated from time of diagnosis of metastases until patient last follow-up or death.
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FIGURE 2.
OS according to age and extent of metastases estimated from time of diagnosis of metastases until patient last follow-up or death.

TABLE 1

Clinical Characteristics of Patient Population

Characteristic	GR (n = 231)	MSKCC (n = 121)	GR + MSKCC (n = 352)	P
Sex (%)
Female	153 (66)	68 (56)^*	221 (63)	0.09
Primary thyroid tumor
Median age at diagnosis (y)	40 (range, 5–90)	49 (range, 7–77)	42 (range, 5–90)	0.03
Histology (%)
Follicular thyroid carcinoma	74 (32.0)	32 (26.5)	106 (30.1)
Papillary thyroid carcinoma	156 (67.5)	89 (73.5)	245 (69.6)	Not significant
Other	1 (0.3)	0	1 (0.3)
Distant metastases
Median age at diagnosis (y)	42 (range, 6–90)	53 (range, 10–80)	46 (range, 6–90)	<0.01
Median year of diagnosis	1994 (range, 1981–2007)	2000 (range, 1983–2008)	1997 (range, 1981–2008)	<0.0001
Synchronous metastases (%)^†	143 (61.9)	67 (55.4)	210 (59.7)	Not significant
Site (%)
Lung	139 (60.2)	66 (54.6)	205 (58.2)
Bone	55 (23.8)	29 (24.0)	84 (23.9)	Not significant
Lung and bone (± others)	37 (16.0)	26 (21.5)	63 (17.9)
Metastases size (%)
Macronodular lung metastases	37 (21.5)	31 (35.6)	68 (26.3)	0.02
Multiple bone lesions	62 (68.9)	41 (77.4)	103 (72.0)	Not significant
Extent of metastases^‡
Category 1	69 (29.9)	14 (11.6)	83 (23.6)
Category 2	66 (28.6)	43 (35.5)	109 (31.0)	<0.001
Category 3	96 (41.6)	64 (52.9)	160 (45.4)

↵* Not known, 2 patients.
↵† 6 mo before or after primary tumor diagnosis.
↵‡ According to Durante classification (8).
Category 1 = patients with metastases on ¹³¹I WB scan but with normal radiologic imaging; category 2 = patients with micronodular lung metastases defined radiologically < 1 cm or with a single bone metastasis identified radiologically; category 3 = macronodular lung metastases or multiple bone metastases or both bone and lung metastases.
Data in parentheses are percentages unless otherwise indicated.

TABLE 2

Median Number of ¹³¹I Treatments, Median Administered Activity, and Median Cumulative Activity (GBq) According to Patient Group

	Group 1 (n = 106)		Group 2 (n = 114)		Group 3 (n = 132)
Parameter	GR (n = 79)	MSKCC (n = 27)	GR (n = 74)	MSKCC (n = 40)	GR (n = 78)	MSKCC (n = 54)
5-y OS	0.96 (95% CI, 0.88–0.99)	0.96 (95% CI, 0.73–0.99)	0.92 (95% CI, 0.83–0.97)	0.87 (95% CI, 0.71–0.94)	0.70 (95% CI, 0.58–0.80)	0.65 (95% CI, 0.50–0.77)
¹³¹I treatment
Median number	4 (1–14)	2 (1–7)	4 (1–14)	3 (1–9)	4 (1–13)	3 (1–8)
Median administered activity (GBq)	3.7 (1.4–5.2)	7.5 (2.7–14.1)	3.7 (1.1–8.7)	8.9 (4.6–18.6)	3.7 (1.8–11.1)	10.6 (3.7–16.7)
Median cumulative activity (GBq)	14.8 (3.7–39.2)	17.2 (2.7–56.4)	14.8 (2.2–52.5)	23.1 (5.5–112)	14.8 (1.8–52.5)	29.8 (3.7–83.9)

Group 1 = patients aged < 40 y with no visible disease on cross-sectional imaging, micronodular lung metastases or single bone lesion; group 2 = patients aged < 40 y with either macrometastases or patients aged > 40 y with micrometastases; group 3 = patients aged > 40 y with lung macrometastases or multiple bone metastases (8).
Data in parentheses are ranges unless otherwise indicated.

TABLE 3

Univariate and Multivariate Analyses of Factors Predicting OS

Factor	No. of subjects/deaths	Crude RR	P	Adjusted RR	P
Sex
Male	129/57	1 (ref)	<0.001	1 (ref)	<0.001
Female	221/55	0.42 (0.29–0.62)		0.49 (0.33–0.74)
Age at the diagnosis of distant metastasis (y)
0–29	80/3	1 (ref)		1 (ref)
30–39	54/11	6.43 (1.79–23.10)		4.54 (1.24–16.61)
40–49	56/18	9.87 (2.91–33.52)	<0.0001	7.65 (2.22–26.32)	<0.0001
50–59	70/31	21.57 (6.55–71.10)		11.49 (3.33–39.59)
60–69	57/31	23.60 (7.15–77.95)		13.18 (3.83–45.31)
70–90	35/18	42.88 (12.39–148.37)		23.03 (6.24–85.08)
Extent of metastases
Category 1	83/8	1 (ref)		1 (ref)
Category 2	109/31	3.65 (1.68–7.94)	<0.001	2.71 (1.22–6.03)	<0.01
Category 3	160/73	8.43 (4.04–17.58)		3.49 (1.56–7.81)
Site of metastases
Lung	205/51	1 (ref)		1 (ref)
Bone	84/32	2.17 (1.38–3.39)	<0.001	1.33 (0.77–2.31)	0.24
Lung and bone ± other	63/29	3.58 (2.24–5.72)		1.63 (0.92–2.91)
Histology
Papillary thyroid carcinoma	245/72	1 (ref)		1 (ref)
Follicular thyroid carcinoma	107/40	1.61 (1.09–2.39)	0.02	0.67 (0.42–1.07)	0.09
Center
GR	231/68	1 (ref)		1 (ref)
MSKCC	121/44	1.77 (1.20–2.62)	0.01	1.41 (0.87–2.29)	0.16

ref = reference; Category 1 = patients with metastases on ¹³¹I WB scan but with normal radiologic imaging; category 2 = patients with micronodular lung metastases defined radiologically < 1 cm or with a single bone metastasis identified radiologically; category 3 = macronodular lung metastases or multiple bone metastases or both bone and lung metastases.
Data in parentheses are 95% CIs.