Differences and analogies in thyroid cancer discovered incidentally or by thyroid-related screening. A multicenter study

Objective: The prevalence of thyroid cancer (TC) has increased worldwide, and an association with metabolic and cardiovascular disorders has been reported. Moreover, an increasing percentage of patients are currently diagnosed incidentally through non-thyroid-related imaging for other clinical conditions. Our aim was to assess the prevalence of thyroid-related disease (TD) versus incidental diagnosis (ID) pre-surgery reasons leading to TC diagnosis and to compare the two groups in terms of clinical characteristics, size and severity of TC at presentation and rate of non-thyroid cancers and cardiovascular/metabolic comorbidities. Design: We performed a retrospective cohort study in three high-volume hospital-based centers for thyroid diseases (Pavia, Latina and Messina) in Italy. Patients: Consecutive patients with TC were included. Measurements: Data on pre-surgery reasons leading to TC diagnosis, age, sex, BMI, presence of cardiometabolic comorbidities and non-thyroid cancer were collected. Results: Among the 327 enrolled subjects, the diagnosis of TC was prompted by thyroid-related reasons in 262 (80.1%, TD group) and incidental in 65 (19.9%, ID group). The ID group patients were more frequently males, significantly older and with a higher BMI than the TD group ones; they had a higher rate of non-thyroidal cancers and cardiovascular/metabolic comorbidities. No significant differences could be observed in terms of TC histotype, cancer size, extrathyroidal extension, lymph node metastases, AJCC staging or American Thyroid Association (ATA) risk stratification. Conclusions: Biological features of TC are similar in the TD and ID groups, but patients in the two groups display significant differences regarding their clinical features.