Neck ultrasounds were done 6 and 12 months after surgery to evaluate for evidence of persistent or recurrent cancer. Persistent cancer was defined as an unstimulated thyroglobulin >0.2 ng/ml, abnormal neck ultrasound, or persistent elevation of thyroglobulin antibodies at 6 months after initial therapy. Recurrent cancer was defined as evidence of cancer following previous achievement of an undetectable thyroglobulin level, negative thyroglobulin antibodies, and negative ultrasound.
The average patient age was 45 years-old and the majority of patients were female (74.6%) and white (92.5%). More than half of the patients (53.7%) received radioactive iodine therapy following surgery. Overall, 49.3% of patients had an excellent response to treatment with an unstimulated thyroglobulin level of ≤0.2 ng/ml, with 60% of them not receiving radioactive iodine therapy. Of these, 96.7% maintained an undetectable unstimulated thyroglobulin at 6 months and 94.1% at one year. All patients that received radioactive iodine therapy had an undetectable unstimulated thyroglobulin level both at 6- and 12-months following surgery.
Additionally, 69% of patients with an early postoperative unstimulated thyroglobulin higher than 0.2 ng/ml and up to 2.0 ng/ml achieved a goal of ≤0.2 ng/ml at 6 months if they received radioactive iodine therapy, compared to only 15.4% if they didn’t receive radioactive iodine therapy. Only 30.8% of patients with an early postoperative unstimulated thyroglobulin >2.0 ng/ml achieved a goal of ≤0.2 ng/ml at 6 months if they received radioactive iodine therapy, compared to only 25.0% if they didn’t.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study shows that early postoperative unstimulated thyroglobulin levels can be used to predict use of radioactive iodine therapy in patients with papillary thyroid cancer. Even though these findings are from a single institution, they are important for two main reasons: 1) this practice can help to decrease overtreatment with radioactive iodine therapy in patients who have low risk disease and 2) it can aid in identifying presence of persistent disease early in the treatment process. In the future, population-based studies can reinforce these results and help with personalizing treatment in patients with papillary thyroid cancer.
— Maria Papaleontiou, MD