From the Guidelines
Elevated Anti-Thyroglobulin (Anti-Tg) antibodies are highly suspicious for persistent or recurrent thyroid cancer, particularly in patients with a history of differentiated thyroid cancer (DTC) 1.
Relationship between Anti-Tg antibodies and thyroid cancer
- The presence of elevated Anti-Tg antibodies can indicate small nodal metastases that may not be detectable on imaging studies 1.
- Rising Anti-Tg antibody levels over time are associated with a higher risk of recurrence and may prompt further imaging and treatment 1.
- The American Thyroid Association risk categories of recurrence can help guide the management of patients with elevated Anti-Tg antibodies, with high-risk patients requiring more frequent imaging and follow-up 1.
Management of elevated Anti-Tg antibodies
- Patients with elevated Anti-Tg antibodies should undergo regular neck ultrasound and thyroglobulin measurement to monitor for signs of recurrence 1.
- In some cases, further imaging studies such as FDG-PET or CT scans may be necessary to evaluate for distant metastases 1.
- Treatment options for patients with recurrent thyroid cancer and elevated Anti-Tg antibodies may include surgery, radioactive iodine therapy, or systemic therapy 1.
From the Research
Relationship Between Elevated Anti-Thyroglobulin Antibodies and Thyroid Cancer
- Elevated Anti-Thyroglobulin (Anti-Tg) antibodies have been found to be associated with a higher risk of lymph node metastasis and cancer persistence/recurrence in patients with differentiated thyroid cancer (DTC) 2.
- A study found that patients with positive Anti-Tg antibodies had a higher recurrence rate compared to those with negative Anti-Tg antibodies 3.
- The presence of Anti-Tg antibodies can interfere with the measurement of thyroglobulin (Tg), making it challenging to monitor patients for residual or recurrent disease 4, 5.
- However, the persistence of Anti-Tg antibodies, especially if levels are rising, may indicate persistent, recurrent, or progressive thyroid cancer, while declining Anti-Tg antibody levels may indicate reduced tumor burden or the absence of disease 5.
- A retrospective study found that high post-operative Anti-Tg antibody levels and central compartment lymph nodal metastases are risk factors for incomplete response, and radioiodine therapy can lead to a significant fall in Anti-Tg antibody levels 6.
Clinical Significance of Elevated Anti-Tg Antibody Levels
- Elevated Anti-Tg antibody levels can be due to thyroid cancer, but also due to exogenous immunoglobulin administration, making it difficult to identify DTC recurrence 4.
- A study found that patients with raised Anti-Tg antibody levels had a good clinical outcome and were not associated with increased mortality 6.
- The level of raised Anti-Tg antibodies was found to be associated with the risk of recurrence, with very high baseline levels (> 1000 IU/ml) being associated with recurrences 6.
Monitoring and Treatment Paradigms
- The approach to follow-up of patients with DTC and positive Anti-Tg antibodies involves monitoring Anti-Tg antibody levels and using alternative methods such as liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure Tg levels 4, 5.
- Radioiodine therapy can be effective in reducing Anti-Tg antibody levels and improving clinical outcomes in patients with DTC and raised Anti-Tg antibody levels 6.