BackgroundLarge scale epidemiology studies have suggested obesity may increase the risk of thyroid cancer, though no prospective analyses using real-world measurement of BMI at a time proximate to initial thyroid nodule evaluation have been performed.MethodsWe performed a prospective, cohort analysis over 3 years of consecutive patients presenting for thyroid nodule evaluation. We measured BMI proximate to the time of initial evaluation and correlated this with the final diagnosis of benign or malignant disease. We further correlated patient BMI with aggressivity of thyroid cancer, if detected.ResultsAmong 1,259 consecutive patients with clinically relevant nodules, 199(15%) were malignant. BMI averaged 28.6 kg/m2 (SD: 6.35, range:16.46-59.26). There was no correlation between the measurement of BMI and risk of thyroid cancer (p=0.58) as mean BMI was 28.9 kg/m2 and 28.6 kg/m2 in cancerous and benign cohorts, respectively. Similarly, BMI did not predict aggressive thyroid cancer (p=0.15). While overall nodule size was associated with increased BMI (p<0.01), these data require further validation as obesity may hinder nodule detection until large.ConclusionIn contrast to findings published from large scale association studies drawn from national databases, these prospective data of consecutive patients presenting for nodule evaluation detect no association of obesity (as measured by BMI) with thyroid cancer. Real time measurement of BMI at the time of thyroid nodule evaluation does not contribute to cancer risk assessment.

Context Predictive models of thyroid nodule cancer risk are presently based upon nodule composition, echogenicity, margins, and the presence of micro-calcifications. Nodule shape has shown promise to be an additive factor helping determine the need for nodule biopsy. Objective We sought to determine if calculation of a nodule’s spherical shape independently associates with cancer risk. Design Prospective cohort study. Setting Single, large academic healthcare system in the US. Patients Patients with 1 or 2 clinically relevant thyroid nodules (predominantly solid and over 1 cm) presenting for diagnostic evaluation. Interventions Thyroid ultrasound, cytological evaluation with fine needle biopsy, and/or histopathological examination on occasion of thyroid surgery. Main outcome measures Calculation of a nodule’s long-to-short ratio (spherical shape), and association with tissue proven benign or malignant endpoints. Results The long-to-short nodule ratio was significantly lower in malignant compared to benign nodules indicating greater risk of malignancy in more spherical nodules [1.63±0.38 for malignant nodules vs 1.74±0.47 for benign, p<0.0001]. The risk of malignancy continually increased as the long-to-short ratio approached a purely spherical ratio of 1.0 [ratio >2.00, 14.6% cancer; ratio 1.51-2.00, 19.7%; ratio 1.00-1.50, 25.5%, p<0.0001]. In multiple regression analysis, younger age, male sex, and nodule's spherical shape were each independently associated with cancer risk. Conclusions The more a thyroid nodule is spherically shaped, as indicated by a long-to-short ratio approaching 1.0, the greater its risk of malignancy. This was independent of age, sex and nodule size. Incorporating a nodule’s sphericity in the risk stratification systems may improve individualized clinical decision-making.

Background: Planar scintigraphy has long been indicated in patients receiving I-131 therapy for thyroid cancer to determine the anatomic location of metastases. We studied our experience upon implementing additional SPECT-CT scanning in these patients. Method: We performed a retrospective study of consecutive adult patients with newly diagnosed thyroid cancer treated with I-131 between 2011 and 2017. Radiologic findings detected with planar scintigraphy alone versus those identified with SPECT- CT scanning were primary endpoints. Result: 212 consecutive patients with thyroid cancer were analyzed in two separate cohorts (107 planar scintigraphy alone;105 planar scintigraphy with SPECT-CT). The addition of SPECT-CT resulted in more findings, both thyroid-related and incidental. However, we identified only 3 of 21 cases in which SPECT- CT provided unequivocal additional benefit by changing clinical management beyond planar scintigraphy alone. No difference in the detection of distant metastatic disease or outcome was identified between cohorts. Conclusion: Synergistic SPECT-CT imaging in addition to planar nuclear scintigraphy adds limited clinical value to thyroid cancer patients harboring low risk of distant metastases, while frequently identifying clinically insignificant findings. These data from a typical cohort of patients receiving standard thyroid cancer care provide insight into the routine use of SPECT-CT in such patients.