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The history of a patient may increase the likelihood of that patient having
a malignant lesion, although for the majority of subjects presenting with
one or more thyroid nodules, the history is not helpful in determining
the nature of the underlying pathology. Prior exposure to radiation is
a risk factor for both benign and malignant nodular thyroid disease (8),
and patients with such a history should be evaluated with care. There are
conflicting reports regarding the effect of age on cancer risk (12) but
thyroid nodules are uncommon in childhood and their presence should be
viewed with suspicion (13). Likewise, there may be an increased risk of
cancer in nodules developing over the age of 65 years, and undifferentiated
thyroid cancer generally occurs in this age group. Sex is itself an important
determinant of neoplasia risk, since thyroid cancer is relatively more
common in thyroid nodules presenting in males rather than females. A family
history of thyroid cancer, especially medullary cancer, may be especially
pertinent and should lead to a suspicion of multiple endocrine neoplasia
syndrome type II or familial medullary thyroid cancer.
A history of symptoms such as dysphagia, dyspnoea or hoarseness may suggest local invasion from a malignant lesion, although such symptoms also occur with benign thyroid enlargement, especially in association with large multinodular goitres. A malignancy rate of 71% has been reported in a group classified "high risk" on the basis of symptoms suggesting a compressive lesion, as well as signs such as firmness, fixation to adjacent structures, vocal cord paralysis and cervical lymphadenopathy (14), although fewer than 5% of patients presenting with nodular thyroid disease have such symptoms or signs (15). While it is recognised that thyroid cancer is less common in multinodular goitre than in clinically solitary thyroid nodules, review of our own consecutive series of 461 patients presenting to a specialist thyroid clinic with thyroid enlargement revealed a significant prevalence of neoplasia in those with multinodular or diffuse thyroid enlargement as well as in those with solitary nodules, determining that further investigation of those with multinodular and diffuse goitre, at least amongst a population referred to hospital, is justified (15). No laboratory test specifically distinguishes benign from malignant thyroid enlargement. Circulating concentrations of thyroid hormones and TSH should, however, be measured, to exclude hyper- or hypothyroidism which themselves warrant specific treatment, and which if present markedly reduce the likelihood of any thyroid enlargement reflecting thyroid neoplasia. Serum concentrations of thyroglobulin are raised in patients with goitre, but values are similar in those with benign and malignant nodules (16). Measurement of serum thyroglobulin is therefore of no value in the initial assessment of the patient presenting with nodular thyroid disease, although its role in the long-term follow up of patients treated for differentiated thyroid cancer is clear. Serum calcitonin is the tumour marker for medullary thyroid cancer and while this diagnosis accounts for less than 10% of thyroid malignancies, it has recently been suggested that routine measurement of serum calcitonin has a role in the work up of patients presenting with nodular thyroid disease (17). While measurement of serum calcitonin in patients with a family history of medullary thyroid cancer is clearly indicated, further studies are needed to determine whether the prevalence of the disease and the relevance of early diagnosis justify routine measurement of circulating calcitonin (18). |
