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Post treatment TgAb-positive titers increased recurrence risk in PTC
In patients with papillary thyroid cancer, those whose post-thyroidectomy blood work was positive for anti-thyroglobulin antibody titers in the year after surgery appear to be at higher risk for disease recurrence, according to data published in Thyroid.
Conversely, negative titers at 1 year were associated with more favorable long-term outcomes.
In the multicenter, retrospective study, researchers evaluated 220 patients diagnosed with papillary thyroid cancer (PTC) between January 1990 and June 2009. The patients, who were identified from among 10 hospital-based thyroid disease referral centers in Italy, all had positive anti-thyroglobulin antibody (TgAb) titer assays at some point between 1 and 12 months after undergoing total or near-total thyroidectomy. The TgAb-positive group (mean age, 45.9 years) was 85% female. A control group consisting of 1,020 patients with PTC and consistently negative results on TgAb titer assays was also included. The baseline percentage of high-risk patients (6.9% vs. 3.2%; P<.05) and extrathyroidal tumor growth (28.2% vs. 24%; P<.00001) were higher in the TgAb-negative group.
At the 1-year follow-up visit, the researchers assessed the success of the primary PTC treatment in all patients. The researchers categorized patients as being without evidence of disease if they demonstrated no residual tumor tissue identified by ultrasound of the neck or other imaging tests. Additionally, the researchers evaluated the effect on clinical outcome of early positive titers that disappeared within the course of the study.
The researchers found that patients in the TgAb-positive group were more likely to have persistent disease (13.6% vs. 7%; P=.0001) at the 1-year follow-up visit or disease relapse during ensuing follow-up (5.8% vs. 1.4%; P=.0001). There was a significant difference at the final follow-up in percentage of patients with either persistent or recurrent disease in the two groups (6.4% of TgAb-positive patients vs. 1.7% in the TgAb-negative group; P<.0001).
Stabilization of TgAb titers was seen in 86 of the 220 TgAb-positive patients at the 1-year visit, and these patients were found to have a significantly decreased rate of persistent disease than those who continued to have TgAb-positive titers (8.2% vs. 17.3%; P=.05).
“Our findings clearly indicate that PTC patients with positive serum TgAb titers after primary treatment have more aggressive disease and less favorable long-term outcomes than demographically similar patients without circulating TgAbs,” the researchers wrote. “Our findings also tend to confirm the favorable prognostic significance of early normalization of serum TgAb titers reported by several groups.”
Disclosure: The researchers reported no relevant financial disclosures.
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