Natural History and Tumor Volume Kinetics of Papillary Thyroid Cancers During Active Surveillance.

Importance: Active surveillance of low-risk papillary thyroid cancer (PTC) is now an accepted alternative to immediate surgery, but experience with this approach outside of Japan is limited. The kinetics (probability, rate, and magnitude) of PTC tumor growth under active surveillance have not been well defined. Objective: To describe the kinetics of PTC tumor growth during active surveillance. Design, Setting, and Participants: Cohort study of 291 patients undergoing active surveillance for low-risk PTC (intrathyroidal tumors ≤1.5 cm) with serial tumor measurements via ultrasonography at a tertiary referral center in the United States. Intervention: Active surveillance. Main Outcomes and Measures: The cumulative incidence, rate, and magnitude of the change in tumor diameter or volume, as well as associations with patient and tumor characteristics. Results: Of the 291 patients, 219 (75.3%) were women; mean (SD) age was 52 (15) years. During a median (range) active surveillance of 25 (6-166) months, growth in tumor diameter of 3 mm or more was observed in 11 of 291 (3.8%) patients, with a cumulative incidence of 2.5% (2 years) and 12.1% (5 years). No regional or distant metastases developed during active surveillance. In all cases, 3-dimensional measurements of tumor volume allowed for earlier identification of growth (median, 8.2 months; range, 3-46 months before increase in tumor diameter). In multivariable analysis, both younger age at diagnosis (hazard ratio per year, 0.92; 95% CI, 0.87-0.98; P = .006) and risk category at presentation (hazard ratio for inappropriate, 55.17; 95% CI, 9.4-323.19; P < .001) were independently associated with the likelihood of tumor growth. Of the tumors experiencing volume growth, kinetics demonstrated a classic exponential growth pattern, with a median doubling time of 2.2 years (range, 0.5-4.8 years; median r2 = 0.75; range, 0.42-0.99). Conclusions and Relevance: The rates of tumor growth during active surveillance in a US cohort with PTCs measuring 1.5 cm or less were low. Serial measurement of tumor volumes may facilitate early identification of tumors that will continue to grow and thereby inform the timing of surveillance imaging and therapeutic interventions.

Cardiac metastasis from thyroid carcinoma.

Cardiac metastasis from epithelial thyroid cancer is a very rare and potentially serious complication. We have identified only 54 reported cases over a 130-year period. Here we review this literature. Cardiac metastases are frequently asymptomatic, but when symptoms develop these tend to be severe and often fatal. The prognosis of cardiac metastases from thyroid cancer is unclear as survival data are often missing or absent in reported cases. However, as many patients died suddenly from cardiac complications, the prognosis seems poor. Of those patients who survived, all underwent surgical intervention. Trans-thoracic echocardiography is the diagnostic modality of choice as it allows dynamic evaluation of intracardiac masses. Metastatic involvement of the heart from thyroid cancer is uncommon. Left untreated this complication seems likely to be fatal. Therefore, in patients with established thyroid malignancy who develop cardiac arrhythmias, new murmurs, or signs of cardiac decompensation, we suggest that cardiac metastases be considered. Echocardiography should be performed in patients with advanced thyroid cancer and cardiac symptoms or signs. If a cardiac metastasis is present, we recommend surgical intervention if possible.