Thyroid cancers incidentally detected at imaging in a 10-year period: how many cancers would be missed with use of the recommendations from the Society of Radiologists in Ultrasound?
OBJECTIVE
To estimate the prevalence of incidental thyroid cancer (ITC) among patients undergoing thyroid surgery and to apply the Society of Radiologists in Ultrasound (SRU) guidelines to ITC.


METHODS
This HIPAA-compliant study was approved by the institutional review board, with waiver of the need to obtain informed consent. A retrospective review of data in patients who underwent thyroid surgery between January 1, 2003, and December 31, 2012, was performed. Imaging studies and reports were reviewed for ITCs that were first detected at either ultrasonography (US) or a different imaging modality and that included US as part of the work-up. ITCs were categorized by using the SRU guidelines to determine the characteristics of SRU criteria-positive and SRU criteria-negative malignancies. Patient demographic data, tumor histologic findings, tumor size, and tumor stage were compared for the SRU criteria-positive and SRU criteria-negative cancers by using the unpaired t test and the χ(2) test.


RESULTS
Among 2090 patients who underwent thyroid surgery, 680 had thyroid cancer; of these patients, 101 (15%) had imaging-detected ITC. The SRU recommendations were applied to the findings in 90 of the 101 patients who had undergone US with images or had reports available for review. Sixteen (18%) of the 90 patients had SRU criteria-negative tumors, which represented 2% (16 of 680) of all thyroid cancers. SRU criteria-negative tumors were smaller than SRU criteria-positive tumors (mean, 1.1 cm [range, 0.9-1.4 cm] vs mean, 2.5 cm [range, 1.0-7.6 cm]; P < .001) and were more likely to be stage I (15 [94%] of 16 vs 47 [64%] of 74; P = .02).


CONCLUSIONS
Imaging-detected ITCs are uncommon. Two percent (16 of 680) of malignancies would not undergo fine-needle aspiration biopsy or surgery if the SRU guidelines were used for work-up of incidental thyroid nodules. SRU criteria-negative tumors are lower in stage than SRU criteria-positive tumors.
From the Department of Radiology, Division of Neuroradiology (M.B., J.K.H.) and Division of Abdominal Imaging (R.C.N.), and the Department of Surgery, Division of Surgical Oncology (J.A.S.), Duke University Medical Center, Box 3808, Erwin Rd, Durham, NC 27710; Department of Radiology, Division of Neuroradiology, Walter Reed National Military Medical Center, Bethesda, Md (H.A.H.); and Department of Surgery, University of Illinois at Chicago, Chicago, Ill (N.M.W.).
Manisha
M
Bahl
Julie A
JA
Sosa
Rendon C
RC
Nelson
Hasan A
HA
Hobbs
Nathan M
NM
Wnuk
Jenny K
JK
Hoang
D044963:Biopsy, Fine-Needle; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D033162:Incidental Findings; D008297:Male; D009657:North Carolina / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000601:surgery; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000601:surgery; D013965:Thyroidectomy; D014463:Ultrasonography