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The Natural History of Benign Thyroid Nodules

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Friday, we discussed the UBER sexy topic of thyroid nodules:

Durante et al, “The Natural History of Benign Thyroid Nodules,” JAMA. 2015; 313(9):926-935

Why do we care?

We all have “that patient” who has to get repeat thyroid ultrasounds and aspirations for either a nodule or multinodular disease. More than 90% of detected nodules are clinically insignificant benign lesions, but we are picking up more thyroid nodules everyday with our non-evidence-based annual physicals and incidentalomas on CT/MRI.

Currently, established guidelines for initial biopsy include:

– nodule size: > 1 cm

– sonographic characteristics: hypoechogenicity, irregular margins, taller-than-wide shape, intranodular vascular spots, microcalcifications

Furthermore, current guidelines recommend serial ultrasound exams for benign thyroid nodules and repeat needle biopsy if a nodule grows by 20%. The problem is that not much is known about the correlation between nodule growth and actual cancer.

This was a prospective study that followed some middle-aged Italian folks over five years with benign nodules, confirmed via laboratory testing and needle aspiration at the baseline evaluation. They received serial ultrasounds and a needle aspiration if they experienced nodule growth of 20% or if the ultrasound met the above-mentioned criteria for biopsy.

P: About a thousand Italian people, with a mean age of 52 years, 82% of whom were female. After loss to follow up and people who no longer met criteria (developed thyroid dysfunction), they were left with 992 patients.

I: This study wasn’t really about an “intervention,” rather it followed growth of nodules over time, so the groups were split into those who experienced growth vs…

C: Those who experienced no growth.

O: In 69% of patients, the thyroid nodules remained stable. 18% shrank spontaneously. In 2%, the nodules *disappeared.* 15% grew, most of which were in patients who had multiple nodules at baseline. 9% developed new nodules. “Over the course of the 5 years, 37% met re-aspiration criteria (growth or concerning features on ultrasound).” (growth or concerning features on ultrasound). Of these, 98.9% confirmed the baseline benign diagnosis.  Thyroid cancer was detected in 0.3% of the 1567 original nodules. 

Limitations:

– 1k patients in the grand scheme of things isn’t a whole lot, but it helps that this study underlines what we already suspected about thyroid nodules

– This doesn’t help us with younger people, in whom thyroid cancer is more prevalent

– 5 years of follow up is a drop in the bucket compared to the usual length of time our patients get follow up (eons) — additional studies should have a longer follow up time

– This was the most boring article EVER. Seriously. OMG.

Bottom Line: Don’t freak out about thyroid nodules! And the guidelines should probably space out ultrasounds because most of them won’t grow, anyway.

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One thought on “The Natural History of Benign Thyroid Nodules

  1. information is good, thanks but I am thinking; population data does not apply to individual data. For example, let’s assume I am in this situation and I take this recommendation and do not worry about or follow up my nodules, which turn out to be the one that grow, turn malignant, or worse yet, one of the aggressive thyroid tumors….this is scary. I really am looking forward to the day that science/medicine will be able to distinguish between those nodules that have malignant capacity and those which do not (if that can be done, as DNA changes are possible anytime contributing to carcinogenesis) prior to recommend the same medical care strategy to all nodules. regards.

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