Serum thyroglobulin may be strong predictor for papillary thyroid carcinoma recurrence
Serum thyroglobulin levels after a lobectomy can be used to predict recurrence risk for adults with papillary thyroid carcinoma, according to findings published in Thyroid.
“Serum thyroglobulin was found to have reasonable value for surveillance in patients after lobectomy, while the value of antithyroglobulin was not significant,” Jie Liu, MD, of the department of head and neck surgical oncology in the National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital at the Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, and colleagues wrote. “According to the receiver operating characteristic curve, over one-fifth of abnormal thyroglobulin patients in the testing cohort had recurrence, in contrast to 2% recurrences observed in normal thyroglobulin patients.”
Researchers conducted a retrospective cohort study of 1,451 adults who underwent lobectomy for papillary thyroid carcinoma at the Chinese Academy of Medical Sciences’ National Cancer Center from 2000 to 2014. Regional and local recurrence was defined through either cytology or pathology. Serum thyroglobulin and antithyroglobulin levels were measured every 6 months after lobectomy for 5 years, and then every 12 months thereafter. Up to five follow-up data points for thyroglobulin levels were included based on equal time intervals for each participant. The study cohort was divided into antithyroglobulin-negative (n = 1,050) and antithyroglobulin-positive (n = 401) subgroups.
After a median follow-up of 72 months, 6.3% of the antithyroglobulin-negative group and 6.6% of the antithyroglobulin-positive group had disease recurrence. There were no deaths in either group during follow-up.
The antithyroglobulin-negative group had a mean first thyroglobulin level of 12.3 ng/mL and a last thyroglobulin level of 9.3 ng/mL. Participants in the antithyroglobulin-positive group had a mean first antithyroglobulin level of 430.3 IU/mL and a final antithyroglobulin level of 340.2 IU/mL.
In an established classifier using serum thyroglobulin to predict recurrence, the area under the curve was 0.81. According to the classifier, last thyroglobulin and its ratio with the second-to-last thyroglobulin level had the best predictive value for recurrence, with an optimal cutoff for last thyroglobulin level of 11 ng/mL. Participants with a last thyroglobulin level of 11 ng/mL or higher had a disease recurrence rate of 23.5%, whereas those with a final thyroglobulin level of less than 11 ng/mL had a 4.4% recurrence rate.
In another receiver operating characteristic curve, the optimal cutoff value of first thyroglobulin level for predicting recurrence was 5.3 ng/mL. People with a first thyroglobulin level of 5.3 ng/mL or greater had a lower recurrence-free survival rate compared with those with a lower level (76.2% vs. 93.3%; P < .001). Elevated first thyroglobulin was associated with worse recurrence-free survival for low- and intermediate-risk participants compared with high-risk patients, and having a first thyroglobulin level higher than 5.3 ng/mL was associated with lower recurrence-free survival (HR = 2.052; 95% CI, 1.231-3.421; P = .006).
For antithyroglobulin levels, the AUC for predicting recurrence was not significant. Further evaluation was not done due to the unfavorable predictive value.
“Despite the presence of residual thyroid tissue, the measurement of serum thyroglobulin has favorable value to predict and detect the presence of recurrence in patients after lobectomy for papillary thyroid carcinoma,” the researchers wrote. “The proposed classifier and the cutoff value of first thyroglobulin and last thyroglobulin can help guide the frequency of monitoring and enable informed clinical decision-making.”
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