Factors Associated With Diagnosis and Treatment of Thyroid Microcarcinomas

Context: Nearly one-third of all thyroid cancers are <= 1 cm. Objective: To determine diagnostic pathways for microcarcinomas vs larger cancers. Design/Setting/Participants: Patients from Georgia and Los Angeles Surveillance, Epidemiology, and End Results (SEER) registries with differentiated thyroid cancer diagnosed in 2014 or 2015 were surveyed. Survey data were linked to SEER data on tumor and treatment characteristics. Multivariable logistic regression analysis was performed. Main Outcome Measures: Method of nodule discovery; reason for thyroid surgery. Results: Of patients who underwent surgery, 975 (38.2%) had cancers <= 1 cm, and 1588 cancers (61.8%) were >1 cm. The reported method of nodule discovery differed significantly between patients with cancers <= 1 cmand those with cancers >1 cm(P < 0.001). Cancer <= 1 cmwas associated with nodule discovery on thyroid ultrasound (compared with other imaging, OR, 1.59; 95% CI, 1.21 to 2.10), older patient age (45 to 54 years vs <= 44, OR, 1.45; 95% CI, 1.16 to 1.82), and female sex (OR, 1.51; 95% CI, 1.22 to 1.87). Hispanic ethnicity (OR, 0.71; 95% CI, 0.57 to 0.89) and Asian race (OR, 0.67; 95% CI, 0.49 to 0.92) were negative correlates. Cancers <= 1 cm were associated with lower likelihood of surgery for a nodule suspicious or consistent with cancer (OR, 0.48; 95% CI, 0.40 to 0.57). Conclusion: Thyroid microcarcinomas are more likely to be detected by ultrasound and less likely to be associated with surgery scheduled for known thyroid cancer. Understanding diagnostic pathways allows for targeted interventions to decrease overdiagnosis and overtreatment.