A marked rise in use of imaging tests after thyroid cancer has been associated with increased treatment for recurrence, but no clear improvement in survival from the disease, finds a study in The BMJ today.
These findings highlight the importance of curbing unnecessary imaging and tailoring imaging after treatment to patient risk, say the researchers.
Over the past two decades, the incidence of thyroid cancer has risen; most of which can be explained by diagnoses of small, low risk cancers. During this same period, the use of imaging after initial treatment has also increased - most likely due to growing concern about the risk of recurrence.
But the relation between imaging, treatment for recurrence, and disease-specific survival remains unknown.
So a team of US researchers used a national cancer database to identify over 28,000 patients diagnosed with thyroid cancer between 1998 and 2011.
They monitored the use of imaging (neck ultrasounds, radioiodine scans and PET scans), additional treatment for recurrence, and deaths due to thyroid cancer until 2013.
Use of neck ultrasounds, radioiodine scans, and PET scans were associated with additional treatment for recurrence, such as surgery, radioactive iodine treatment or radiation therapy. Only the use of radioiodine scans was associated with improved survival from thyroid cancer.
This is an observational study, so no firm conclusions can be drawn about cause and effect and the authors point to several limitations. However, they say it is not clear if the benefits of greater imaging outweigh the financial costs, heightened patient anxiety, and risk of patient harm from the treatment for recurrence.
"In light of the growing incidence of low-risk thyroid cancer and the paradoxical rise in imaging after primary treatment, this study provides the foundation needed to reassess thyroid cancer surveillance patterns and to curb unnecessary imaging," they conclude.