Incidental Thyroid Nodules on CT: Evaluation of 2 Risk-Categorization Methods for Work-Up of Nodules

X.V. Nguyen; K. Roy Choudhury; J.D. Eastwood; G.H. Lyman; R.M. Esclamado; J.D. Werner; J.K. Hoang

doi:10.3174/ajnr.A3487

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Fig 1.
Cause-specific survival curves as a function of tumor size for thyroid cancers in the SEER data base. This represents method A of risk categorization.
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Fig 2.
Cause-specific survival curves of thyroid cancers in SEER stratified by the 3-tiered system (method B).

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Table 1:

Survival of patients with thyroid carcinoma by patient demographics and tumor characteristics

	Percentage Total	10-Year Relative Survival (%)	95% CI	10-Year Thyroid Cancer–Specific Survival (%)	95% CI
Total	100%	97.4	97.0–97.7	95.7	95.5–95.9
Sex
Male	23%	93.8	92.9–94.7	92.0	91.4–92.5
Female	77%	98.4	98.0–98.6	96.8	96.6–97.0
Age (yr)
0–19	2.2%	99.1	98.3–99.5	99.3	98.7–99.6
20–34	21%	99.3	98.9–99.5	99.7	99.5–99.8
35–49	36%	99.3	98.9–99.5	98.9	98.7–99.0
50–64	27%	96.2	95.3–96.9	94.6	94.1–95.1
≥65	15%	90.3	88.1–92.1	81.0	79.9–82.0
SEER summary stage
Localized or unstaged	61%	99.9	99.8–99.9	99.0	98.9–99.1
Regional	35%	95.6	95.0–96.2	94.4	94.0–94.8
Distant	4.1%	56.1	53.5–58.5	58.2	56.0–60.4
Tumor size (mm)
<5	12%	99.9	99.7–99.9	99.4	99.0–99.6
5–10	14%	99.8	99.6–99.9	98.9	98.6–99.2
10–14	15%	99.8	99.5–99.9	99.0	98.7–99.2
15–19	13%	99.8	99.5–99.9	98.3	97.9–98.6
20–29	20%	99.4	98.3–99.8	97.0	96.7–97.4
30–39	11%	96.6	95.5–97.4	95.2	94.6–95.7
≥40	14%	84.0	82.7–85.2	83.3	82.4–84.2

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Table 2:

Survival in patients with thyroid malignancy in the SEER data base using risk-categorization methods of size cutoff (method A) and the 3-tiered system (method B)^a

	Percentage Total	10-Year Relative Survival (%)	95% CI	10-Year Thyroid Cancer-Specific Survival (%)	95% CI
Method A (size cutoff)
≥10 mm	74%	96.4	96.0–96.7	94.7	94.4–94.9
<10 mm	26%	99.8	99.7–99.9	99.1	98.9–99.3
≥15 mm	59%	95.4	94.9–95.8	93.7	93.4–94.0
<15 mm	41%	99.8	99.8–99.9	99.1	98.9–99.2
≥20 mm	46%	94.1	93.5–94.6	92.4	92.0–92.7
<20 mm	54%	99.9	99.8–99.9	98.9	98.7–99.0
Method B (3-tiered risk categories)
Categories 1, 2, and 3	74%	96.0	95.6–96.3	94.6	94.3–94.8
Category 1	39%	91.5	90.9–92.1	90.7	90.3–91.1
Category 2	13%	99.7	99.2–99.9	99.9	99.7–99.9
Category 3	23%	99.8	99.7–99.9	98.0	97.7–98.3
Not categorized	26%	99.9	99.8–99.9	99.5	99.3–99.7

↵a Nodules smaller than the size cutoff and in the “not categorized” group for method B would represent nodules that would not receive work-up if the methods were applied.

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Table 3:

Comparison of capture rates of incidental thyroid nodules by methods A and B^a

Categorization Method	Patients	Total
Method A (size cutoff)
≥10 mm	57	43%
<10 mm	76	57%
≥15 mm	22	17%
<15 mm	111	83%
≥20 mm	12	9%
<20 mm	121	91%
Method B (3-tiered system)
Category 1, 2, or 3	31	23%
Category 1	2	2%
Category 2	9	7%
Category 3	20	15%
Not categorized	102	77%
Total	133

↵a Incidental thyroid nodules from retrospective CT review were stratified by size cutoff (method A) and the 3-tiered system (method B). The nodules smaller than the size cutoff and in the “not categorized” group for method B would represent nodules that would not receive work-up if the methods were applied.