Essentials of Thyroid Cancer Management
History is rarely helpful in differentiating benign and malignant nodules.
An exception is a history of head and neck irradiation in childhood or teenage years. Another exception is a family history of medullary carcinoma of the thyroid, which should prompt consideration of familial medullary thyroid cancer or multiple endocrine neoplasia type 2, the latter being associated with hyperparathyroidism and phaeochromocytoma.
Physical examination is also rarely helpful in differentiating benign and malignant nodules, unless there is evidence of invasion of other structures in the neck eg, hoarse voice or enlarged regional lymph nodes, which suggest malignancy. An algorithm for investigating thyroid nodules is shown in Box 1. This algorithm may be cut short in patients at high risk of cancer. Measurement of thyroid-stimulating hormone TSH level is helpful, as suppression suggests that a nodule is hyperfunctioning. Some of these patients will also have a raised level of serum free thyroxine T 4.
Hyperfunctioning solitary nodules carry a low risk of malignancy at least in adults. When TSH level is normal, assay of serum free T 4 adds no further information. A raised TSH level in an elderly patient with a large, rapidly growing thyroid mass suggests thyroid lymphoma. Serum calcitonin level should be measured if there is a family history of medullary carcinoma of the thyroid, as a raised level is both sensitive and specific for this cancer. However, this measurement is not cost-effective in the initial evaluation of nodules. Thyroid imaging should not be routine, but should be used to answer a specific clinical question.
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Thyroid scanning using pertechnetate 99M Tc and formerly radioiodine, I was traditionally used to screen thyroid nodules for malignancy. Current recommendations are that patients with TSH suppression should proceed to pertechnetate scanning to confirm that the nodule is hot. The patient can then be treated with therapeutic radioiodine or lobectomy. Pertechnetate scans are thus not advocated for assessing a nodule in patients who are euthyroid or hypothyroid. Thyroid ultrasonography is commonly performed. Although some ultrasonographic features, such as punctate calcification and irregular or blurred margins, suggest papillary carcinoma, routine ultrasonographic studies rarely aid clinical decision-making.
Computed tomography is rarely necessary, but can be useful in delineating the extent of disease in patients with known thyroid cancer. It should be remembered that use of iodinated contrast medium reduces technetium uptake and may reduce the diagnostic utility of pertechnetate scanning. In the absence of TSH suppression, biopsy by fine-needle aspiration should be the first-line investigation for a solitary nodule or a dominant nodule in a multinodular goitre.
The success of a biopsy depends on the adequacy of the specimen and skill of the cytopathologist. The procedure can be done in ambulatory patients without local anaesthesia.
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Discomfort is usually mild. Specimens can be taken from several parts of the nodule, and slides smeared immediately. Immediate staining of some slides allows evaluation of the adequacy of material while the patient is still present and further passes if material is inadequate.
There is a small risk of bleeding, which settles quickly with ice packs. Ultrasound guidance is preferred by some practitioners and is needed for impalpable lesions that warrant fine-needle aspiration biopsy. Larger thyroid nodules are often partially cystic, containing fresh or altered blood.
Aspirates often contain large numbers of macrophages, but follicular cells may be sparse. The more cystic the lesion, the more likely the specimen is to be non-diagnostic. The cytopathological report should be one of the following: insufficient for diagnosis; malignant; atypical; a follicular neoplasm; or benign.
The presence of colloid and bland follicular cells suggests a benign lesion. The report should indicate adequacy of the specimen, as malignancy cannot be excluded if material is insufficient. Papillary and often medullary carcinoma can be recognised on fine-needle aspiration biopsy Box 3 , but follicular adenomas and carcinomas have similar cytological appearance, with diagnosis of malignancy requiring demonstration of capsular or vascular invasion in paraffin sections.
All follicular neoplasms should be excised unless there is clear evidence that the nodule is hyperfunctioning see case report, Box 4. Indications for thyroid surgery thus include malignant or atypical cytology, follicular neoplasm, and failure to obtain a diagnostic sample.
Essentials of Thyroid Cancer Management
Thyroxine suppressive therapy may be used to treat benign nodules. The rationale is that nodule cells may remain responsive to TSH. Given the increased risk of cardiac arrhythmia and evidence that subclinical hyperthyroidism can lead to loss of bone mass in postmenopausal women, 16 TSH suppression should be used cautiously in older patients. Well-differentiated thyroid cancers arise from follicular cells and encompass both papillary and follicular carcinomas. Papillary carcinomas are the most common thyroid cancer.
They are unencapsulated, often multicentric, and bilateral in a third of cases. The most common sites of metastasis are regional lymph nodes and, less commonly, the lungs. They are encapsulated, and the feature of malignancy is invasion of the capsule. Prognosis depends on the degree of invasion and differentiation, with poorly differentiated tumours having poorer outcomes. Follicular carcinomas can metastasise to bone, causing lytic lesions. Factors that worsen prognosis include male sex, advanced age, large tumour, poor differentiation, local invasion and distant metastases.
Thyroidectomy should be performed by an experienced surgeon, as this reduces complications, such as hypoparathyroidism and recurrent laryngeal nerve palsy. Although subtotal thyroidectomy has lower complication rates, thyroid remnant ablation with radioiodine is less successful when large amounts of thyroid tissue remain. This may not only destroy cancer cells in the neck and elsewhere, but also improve specificity of future radioiodine whole-body scans and serum thyroglobulin assays by removing normal thyroid cells.
It is usual practice to perform a whole-body scan at the time of discharge, using the therapeutic radioiodine dose as the imaging agent. This usually demonstrates uptake in the thyroid bed, salivary glands, gastrointestinal tract and bladder. Uptake in other areas indicates metastatic disease Box 5. An algorithm for follow-up after treatment of differentiated thyroid cancer is shown in Box 6.
Clinical and biochemical follow-up: Clinical examination of the thyroid bed and regional lymph nodes may detect recurrence. Serum thyroglobulin levels are used to follow up patients treated by thyroidectomy and radioiodine ablation of the thyroid remnant. Tumour cells generally retain the ability to synthesise thyroglobulin in response to TSH stimulation. Unfortunately, a significantly elevated thyroglobulin level does not predict uptake of radioiodine and, conversely, tumour which concentrates radioiodine may produce insignificant amounts of thyroglobulin.
It is as yet unclear under what conditions rhTSH, an expensive drug, will be made available in Australia. We reserve this scanning for patients with measurable thyroglobulin levels and those with thyroglobulin autoantibodies, in whom thyroglobulin levels cannot be measured. Alternatively, rhTSH injection allows whole body scanning without stopping thyroxine therapy. Other imaging: Where there is evidence of metastatic disease eg, raised thyroglobulin level but no abnormal I uptake is detected on whole-body scan, ultrasonography or computed tomography may locate a tumour mass.
Positron emission tomography using fluorodeoxyglucose may detect lesions not seen on radioiodine scanning, and evidence is emerging that this is a negative prognostic indicator. In metastatic disease, the tumour should be debulked by an experienced surgeon where practical, and radioiodine administered either after surgery or as the primary treatment. Thyroxine suppressive therapy must be resumed after radioiodine therapy and can slow the growth of unresectable disease. This tumour arises from the neuroendocrine C-cells of the thyroid and manufactures calcitonin, with the preoperative level correlating with the burden of disease.
Fifty per cent of patients have lymph node metastases at presentation. Add to Wishlist. USD Sign in to Purchase Instantly.
Thyroid Cancer | Cleveland Clinic
Temporarily Out of Stock Online Please check back later for updated availability. Overview The goal of this book is to provide Endocrinologists, Surgeons, Nuclear Medicine Physicians, and Radiation Oncologists with practical advice about managing patients with thyroid cancer. This book will not replace the excellent publications that focus on a highly speci? These kinds of publications will always be an important source of information for both students and expe- enced practitioners. The void that we see is the lack of a single, concise, up-- date reference that is applicable to all of the specialists who make clinical de- sions about thyroid cancer patients.
Essentials of Thyroid Cancer Management will? For reading ef? We rely heavily on tables, diagrams, graphs, photographs, and other? Subjects are addressed in a large number of chapters that each focus on a relatively narrow topic. In some cases, there is overlap between the information in multiple different chapters so the reader does not have to page back and forth between different sections of the book. As occurs in every area of medicine, there is controversy about important issues in the management of thyroid cancer.