Primary Versus Tertiary Care Follow-Up of Low-Risk Differentiated Thyroid Cancer: Real-World Comparison of Outcomes and Costs for Patients and Health Care Systems

Background: An unprecedented rise in the prevalence of low-risk well-differentiated thyroid cancer (TC) has been reported in several countries, which is partly due to an increased utility of sensitive imaging techniques. The outcome of these cancers has generally remained excellent and the overall 5-year survival is almost 100%. However, the extended follow-up strategy for these patients remains unclear and while the initial management is done in specialist centres some experts opt to follow them on a long-term basis while others discharge them to primary care after the initial management. The effectiveness of one strategy versus the other has not been studied.

Methods: We conducted a real-world comparison to assess the outcome of low-risk TC (AJCC stage I) with undetectable thyroglobulin (TG) 2 years after radio-iodine (I-131) therapy. The outcome from Halifax (NS, Canada) and London (ON, Canada), where all TC patients are routinely followed by the tertiary care team, was compared with that from Edmonton (AB, Canada), where patients are routinely discharged to primary care.

Results: All patients were diagnosed between January 1, 2006, and December 31, 2011. The mean follow-up in primary care after discharge was 62.2 months and in tertiary care it was 64.6 months ( = 0.43). Rates of recurrence were similar in both groups, i.e., 1.1% in primary care and 1.3% in tertiary care ( = 0.69). Ultrasound surveillance was conducted in 56.5% of the patients in primary care and 52.6% of the tertiary care group ( = 0.26). The rate of annual unstimulated TG testing per patient was 0.58 (range 0-14) in primary care and 0.96 (range 0-6) in tertiary care ( = 0.06). More patients in primary care (86%) than in tertiary care (29.9%) consistently had thyroid-stimulating hormone levels within the target range ( < 0.001). The mean healthcare cost, based on a single follow-up visit with a blood test and ultrasound in the primary care group was CAD 118.01 and in the tertiary care group it was CAD 164.12.

Conclusion: Our study shows that extended follow-up of low-risk TC patients is perfectly feasible in primary care and provides significant economic benefit for the healthcare system.