Thyroid Nodules and What They Mean

Lots of people develop dense collections of tissue in their thyroid gland as they age, known as nodules.  In fact, estimates of the prevalence of thyroid nodules range from up to 8% of women and 2% of men with palpable nodules to almost one-third of women when ultrasound is used for screening. Given the abundant use of imaging methodologies such as CT, more and more of these so-called 'incidentalomas' are found  and therefore require follow-up, and there's the rub,  Rick and I agree in PodMed this week. Lots of unnecessary evaluation and treatment, otherwise known in the parlance as overdiagnosis and overtreatment, ensue.  Help may have arrived with a study in NEJM making use of a genetic technique to assess thyroid nodules and perhaps avoid unnecessary surgery.

Almost 4000 patients and almost 5000 fine needle aspiration biopsies of thyroid nodules were included in this study.  All the aspirates came from nodules 1cm or more in size that required further evaluation.  Of these, almost 600 were of indeterminate cytology, which happens in 15-30% of cases,  so 265 were tested using a gene expression classifier.

85 of the aspirates tested using the gene expression classifier turned out to be malignant, with 78 of the 85 correctly identified by this system, giving a 92% sensitivity and a 52% specificity.  Negative predictive values ranged from 85 to 95% for "atypia (or follicular lesion) of undetermined clinical significance,” “follicular neoplasm or lesion suspicious for follicular neoplasm,” or “suspicious cytologic findings.” 

All of the samples used in this analysis were correlated with examination of tissue removed at thyroidectomy.  The authors conclude that this gene expression classifier could be used to recommend watchful waiting rather than thyroidectomy for many patients.  While surgical outcomes following thyroid gland removal are usually good, 2-10% of patients who've undergone thyroidectomy report long term morbidity.   Clearly, lifelong thyroid hormone replacement is needed and may need adjustment.

The test is good news for the up to 30% of people whose fine needle aspirations of thyroid nodules don't point in a clear direction and would otherwise result in surgery, eliminating both unnecessary expense and risk.  Other topics this week include the development of sprue or celiac disease with use of a common blood pressure medication in the Mayo Clinic Proceedings, liver complications due to a medical food in Annals of Internal Medicine, and use of tissue plasminogen activator or TPA in folks already taking the blood thinner coumidin, in JAMA .  Until next week, y'all live well.

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June 29, 2012 at 8:34 pm
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