THYROID CANCER – INVESTIGATIONS
The first step is a proper evaluation based on:
Detailed medical history and Physical examination: After taking a detailed history from the person the doctor examines the thyroid gland for any enlargement or fixation to the underlying or overlying tissue. Principally thyroid gland is felt as a firm, and painless nodule. Examination of lymph nodes in the front of the neck (i.e. anterior cervical group of lymph nodes) may show enlargement.
To help establish the diagnosis of thyroid cancer, the following tests may be advised:
I. Fine Needle Aspiration (FNA) Biopsy
- It is the best way to rule out cancer in a suspicious thyroid nodule. This is performed in the out-patient clinic.
- Usually 2-3 biopsies are taken from the nodule and reading by an experienced pathologist is mandatory.
- FNA biopsy may be repeated if the pathological findings are inconclusive in spite of a clinically suspicious nodule (which occurs at times, if specimen is diluted with blood or with less cells).
- Ultrasound guided FNA biopsy is done in non palpable nodules.
II. Thyroid function test are usually normal unless there is associated thyroiditis. Follicular carcinoma may sometimes secrete increased thyroxine (which suppresses TSH) causing clinical hyperthyroidism.
III. Other blood test
- Serum thyroglobulin test: Serum thyroglobulin is high in most metastatic papillary and follicular tumors. Thus it is useful as a marker for recurrence (reappearance) or spread of cancer. But unexpected thyroglobulin levels should prompt a repeated assay (e.g. thyroglobulin may be misleadingly elevated as in thyroiditis).
- Serum calcitonin levels: This is done if medullary thyroid carcinoma (or cancer) is suspected. The levels are frequentlyincreased in medullary cancer. Serum calcitonin acts as a marker for metastatic disease (spread of cancer)
- Serum carcinoembryonic antigen (CEA) levels: It is usuallyelevated in medullary carcinoma, however not specific for this carcinoma. This is also used as a marker for metastatic (spread of cancer) disease and for assessing the effectiveness of treatment. Rising levels of calcitonin and CEA are the best indicators for recurrence of the disease.
- Genetic testing: As 20% of medullary carcinoma are familial or part of MEN (multiple endocrine neoplasia) type 2, siblings of the patient are advised genetic testing.
IV. Imaging Studies:
- Ultrasound of neck is done to determine the size and location of the tumor as well as to find out neck metastasis (spread of cancer)
- Radioactive iodine scan help in determining whether the tumor is under functioning (cold) or over functioning (hot). “Cold” nodules usually have a higher chance of suspicion for malignancy (or cancer)
- Metastasis (distant spread of cancer) can be detected byPositron Emission Tomography (PET) scanning, Magnetic Resonance Imaging (MRI) and Spiral CT