Imaging tests after primary treatment for thyroid cancer may not lead to improved survival, according to a study published in BMJ.
While incidences of thyroid cancer have continued to grow in recent years, the disease is still generally diagnosed as low-risk, with 96% to 100% of patients surviving at least 10 years. However, imaging tests after primary treatment for thyroid cancer are also being used more often, likely due to fears of recurrence, which ranges from 1% to 68%.
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To determine the relationship between imaging tests after primary treatment of differentiated thyroid cancer and survival, researchers led by Megan R Haymart, University of Michigan (Ann Arbor, MI) examined trends data of patients diagnosed with the disease to see how use of imaging, treatment for recurrence, and survival changed over time.
A total of 28,220 patients diagnosed with differentiated thyroid cancer between 1998 and 2011 were included in the study analysis. Overall, researchers found that imaging after primary treatment was used quite often, with 56.7% of patients undergoing at least one neck ultrasound, 23.9% having a radioiodine scan, and 14.9% undergoing a PET scan. Using a Poisson regression model to account for changing population sizes, researchers also determined that incident cancer, imaging, and treatment recurrence all increased significantly. Additionally, while use of imaging tests had the sharpest growth, there was still no statistically significant change in death rate.
The type of imaging test used was also found to be associated with different treatment modalities. Patients who received ultrasounds were more likely to received additional surgery and radioactive iodine treatment, but not radiotherapy. Radioiodine scans and PET scans were associated with additional surgery, radioactive iodine treatment, and radiotherapy. Further, while neither PET scans nor ultrasounds significantly affected survival, radioiodine scans were associated with improved disease-specific survival.
Thus, researchers concluded that imaging after primary treatment may lead to more treatment for recurrence; however, without an improvement in survival—except for radioiodine scans in presumably iodine avid disease—it is unclear whether additional testing equates to better care. Thus, more research is needed on this subject in the form of long-term clinical trials and cost-effectiveness research.
