|
Thyroid carcinomas have a very marked variability in aggressiveness from
highly differentiated papillary carcinomas to the undifferentiated anaplastic
cancers occuring mainly in older people and with a very poor prognosis.
Thyroid carcinomas are by far the most frequent endocrine gland malignancies
accounting for approximately 0.5-1.5 % of all malignancies. Malignant tumours
of the thyroid gland are of either follicular, parafollicular or stromal
origin(1).
The yearly incidence of thyroid carcinomas is somewhere between 20 and 50 per million inhabitants with approximately 5 deaths per million inhabitants per year. The overall cancer incidence is generally not considered to be influenced by the iodine intake in a population(2), although a study from two regions in Italy has demonstrated a 2 fold increase in thyroid cancer incidence in an iodine deficient area compared to an iodine sufficient one(3). Also, the distribution of the types of thyroid carcinomas is probably related to iodine intake, with a higher proportion of poorly differentiated follicular and anaplastic carcinomas in areas of iodine deficiency while iodine sufficient areas have a higher proportion of the more favourable papillary thyroid carcinoma. Clinically evident thyroid nodules and benign goitres occur frequently depending on the iodine intake of the population. Postmortem examinations and epidemiological surveys of populations with evaluation of the thyroid gland texture by ultrasound have revealed even more clinically non-detectable thyroid nodules. However, most of these nodules are benign, and it is therefore a challenge for the clinician to pick out the few malignant thyroid nodules. If conventional treatment is given the overall survival rate of thyroid carcinomas is high, usually exceeding 90 %, in subgroups of patients with papillary carcinomas even close to 99 %. Thyroid carcinomas may, however, relapse many years after apparently successful initial therapy, and lifelong follow-up care of the thousands of survivors after primary treatment is therefore mandatory(2). The objectives of the present paper are to summarize and discuss the field of thyroid carcinoma from the perspective of the clinical thyroidologist and present knowledge on the following aspects: 1. Pathogenesis of thyroid carcinoma 2. Differential diagnosis from benign thyroid diseases 3. Types and staging of thyroid carcinoma 4. Treatment of thyroid carcinoma 5. Long-term follow-up. 7. Pathogenesis of thyroid carcinoma |
