After definitive therapy for thyroid cancer, patients are followed by an endocrinologist or surgeon or, less commonly, an oncologist. Exactly how the patient is followed and when they are seen depends on the individual physician and the perceived risk of recurrence.
Generally, patients are seen every 3-6 months for 2-3 years then yearly . A careful physical exam and blood tests are performed. Radiology tests, including radioactive iodine total body scanning and ultrasound, are performed as indicated. If an area of concern is found, a minimally invasive biopsy is performed. If it is positive then a therapeutic approach is organized. Occasionally, only blood tests suggest recurrence and treatment with RAI is considered after a complete evaluation.
Specifically, The physician carefully examines the patient with particular attention to the neck, looking for enlarged lymph nodes or other signs of local recurrence. Symptoms such as a cough, a change in voice, trouble swallowing or a focal area of persistent pain may suggest a local recurrence or distant metastasis. A very important blood test is the thyroglobulin assay. Thyroglobulin is a protein made only by thyroid tissue or well-differentiated thyroid cancer. If the patient has had their thyroid gland removed and does not have spread of the cancer into lymph nodes or other organs (distant metastases), this level should be undetectable. Not uncommonly, auto-antibodies associated with chronic inflammation of the thyroid gland (Hashimoto’s thyroiditis) can alter the measured levels of thyroglobulin, so interpretation by an experienced physician is important.
If the thyroglobulin level is elevated after therapy, recurrent thyroid cancer may be present. Usually, an ultrasound of the thyroid bed and the regional lymph nodes is performed. Areas of concern are sampled by FNA. A total body Iodine scan may be performed. A small dose of radioactive iodine is given and the patient is scanned at 24 and 48 hours for evidence of discrete uptake that may indicate metastatic disease. On occasion thyroid cancer may not take up radioactive iodine well and a PET-CT scan may be helpful.
Once the diagnosis is made, then extent of disease must be determined. Recurrent disease may be classified into 3 groups. These groups may overlap.