17 Endocrine tumours
Thyroid cancer
Evaluation
Evaluation includes clinical examination and assessment for thyrotoxicosis which is rare in cancer. Initial investigations include thyroid function tests and FNA of the lesion. Biopsy may be indicated for lymphoma and anaplastic carcinoma and hemithyroidectomy is indicated for all follicular lesions. MRI is the preferred imaging to assess local invasion (Figure 17.1) as the use of iodine containing contrast can cause thyroid stunning which may prevent effective use of radioiodine for at least three months subsequently.
Staging
Box 17.1 shows the TNM staging system. The TNM and MACIS (Box 17.2) have been shown to be the best predictors of outcome in differentiated thyroid cancer.
Box 17.1
TNM staging in thyroid cancer
T stage
| pT1 | Tumour ≤2 cm in greatest dimension |
| pT2 | Intrathyroidal tumour >2–4 cm in greatest dimension |
| pT3 | Intrathyroidal tumour >4 cm in greatest dimension |
| pT4 | Tumour beyond the thyroid capsule |
N stage (cervical and upper mediastinal)
| N0 | No nodes involved |
| N1 | Regional nodal involvement |
| N1a Ipsilateral cervical nodes | |
| N1b Bilateral, midline or contralateral cervical nodes, or mediastinal nodes |
Distant metastases
| M0 | No distant metastases |
| M1 | Distant metastases |
| MX | Distant metastases cannot be assessed |
