Instrumental Diagnostics and Staging
Primary evaluation and staging of neoplasms rely heavily on radionuclide diagnostics. Scintigraphy is a key tool for:
- Assessing the functional activity and nature of thyroid nodules.
- Diagnosing and accurately staging neuroendocrine tumors, specifically medullary thyroid carcinoma.
In modern personalized oncology, radiologists need a deep understanding of anatomy, metastatic pathways, and must consider radiomics (radiomics) and genomics data. A diagnosis of a malignant process or its progression should be made only with a high degree of certainty to avoid overdiagnosis (overdiagnose).
Hormone Therapy in Cancer
Following surgical treatment for tumors, patients require specific medical support. Thyroid hormone medications serve a dual function:
- Levothyroxine sodium is the drug of choice for differentiated thyroid cancer. It is used not only as replacement therapy, but also for suppression. The main goal is to inhibit TSH-dependent growth of residual tumor cells.
- Liothyronine and thyreoidin also have oncological thyroid pathology in their indications and can be used for diagnostic purposes (e.g., suppression tests).
Post-Treatment Follow-Up and Recurrence Monitoring
A history of a malignant neoplasm requires close attention to any persistent or prolonged patient complaints (lethargy, weight loss).
- Statistics: 95% of recurrences develop within the first 2 years after therapy. Meanwhile, tumor markers remain negative in one-third of patients.
- Tactics: CT monitoring is justified during the first two years. An interval of 6–12 months does not worsen the prognosis, although for large tumors, an empirical shortening of the interval between examinations is entirely appropriate.
- Whole-body imaging: When recurrence is suspected, whole-body CT, MRI, or PET/CT is increasingly used. The main risk of such methods is obtaining false-positive results or detecting untreatable recurrences.
Upon confirmation of recurrence, modern cytotoxic chemotherapy shows high efficacy (cure rate exceeds 90%).
Specifics of Detecting Bone Metastases
Thyroid tumors tend to metastasize to the bones. When an oncological patient presents with acute bone pain, radionuclide imaging (bone scan) serves as the primary screening method.
However, the method has limitations: visualization of the lesion requires a pronounced osteoblastic response (osteoblastic response). If the metastasis does not provoke such a reaction, the scintigram may be false-negative. In such situations, when the clinical picture persists and the radionuclide test is clear, MRI becomes the method of choice, capable of detailing areas of low signal in the vertebral bodies and the threat of spinal cord compression.
Class and exam questions
Why is levothyroxine prescribed after removal of differentiated thyroid cancer?
The drug is used not only to replace hormone deficiency, but also as suppressive therapy to inhibit TSH-dependent growth of any remaining cancer cells.
How often do recurrences occur and when should they be expected?
The vast majority of recurrences (95%) occur within the first two years after completing primary treatment. Regular CT monitoring is indicated during this period.
Does a bone scan always detect bone metastases?
No, a sufficient tissue osteoblastic response is required for successful detection. If absent, the result will be false-negative, and an MRI will be needed to clarify the diagnosis.
What should be done if whole-body imaging results are equivocal?
Diagnosing metastasis is a heavy blow for the patient. If the picture is atypical and there is no high degree of certainty, making the diagnosis should be postponed to avoid overdiagnosis.
What else to study on this topic
- Pathophysiology of Osteoblastic Response in Bone Metastases
- Radiomics and Genomics in Personalized Oncology
- Specifics of Whole-Body PET/CT in Searching for Occult Recurrences
- Mechanisms of Action of Cytotoxic Chemotherapy in Cancer Recurrences
- Diagnostic Algorithms for Medullary Thyroid Carcinoma
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