The global epidemic of thyroid cancer overdiagnosis illustrated using 18 months of consecutive nodule biopsy correlating clinical priority, ACR-TIRADS and Bethesda scoring

Low thyroid cancer mortality worldwide has not been altered by decades of increasing radiological, pathological and surgical intervention for thyroid nodules. Ultrasound-based risk stratification of thyroid nodules, such as TIRADS, has been introduced to reduce intervention for the 'global epidemic' of thyroid cancer 'overdiagnosis'. This article illustrates the use of TIRADS at a New Zealand tertiary centre, during its introduction, with all nodules undergoing fine-needle aspiration biopsy (FNAB) correlated with clinical referral priority and cytological Bethesda score. The correlation between TIRADS and Bethesda score was not significant but cytology had a strong association with clinical priority. Accuracy of TIRADS was poor though the risk of malignancy for TIRADS 5 nodules was 5.1 times those rated as TIRADS 3. After TIRADS was introduced, there was no significant trend in the proportion of malignant nodules diagnosed by FNAB. Despite an incomplete TIRADS programme, the ACR targets of malignancy rates were achieved. The number of patients, as well as the number of nodules per patient, referred for FNAB continues to rise. Changing papillary thyroid cancer nomenclature and other control measures by health policymakers, such as adjustments to payment systems, may be justified. Radiologists are wasting precious health resources that can be better deployed. The use of TIRADS is expensive and a symptom of health policy failure. Clear recommendations from professional societies to not report incidental small thyroid nodules may be a useful start. Whether TIRADS merits continuing use and promotion should be further investigated.