6: Thyroid nodules and thyroid cancer.

Thyroid nodules are common clinically (prevalence, about 5%) and even more common on ultrasound examination (about 25%). About 5% of thyroid nodules are malignant. Most thyroid cancers are well-differentiated papillary or follicular tumours with an excellent prognosis (10-year survival, 80%-95%). The incidence of papillary thyroid cancer appears to be increasing on the east coast of Australia. Fine-needle aspiration biopsy of the thyroid is the most cost-effective diagnostic tool. Recommended initial management of all follicular carcinomas and of papillary carcinomas > 1.0 cm is total thyroidectomy followed by radioiodine ablation. Most patients should be managed postoperatively with doses of thyroid hormone sufficient to suppress plasma levels of thyroid-stimulating hormone. Recurrences can occur many years after initial therapy, and follow-up should be lifelong. Thyroid nodules are very common, but have a relatively low risk of malignancy