Surgical treatment of thyroid carcinoma

Abstract

BACKGROUND: Thyroid cancer is usually of follicular cell origin, but medullary thyroid cancer (MTC) arises from the parafollicular or C-cells. The annual incidence of thyroid cancer varies from 3–7 per 100.000 population in Austria and constitutes 1.36 % of all malignant tumours. METHODS: The current surgical treatment of thyroid carcinoma is reviewed with respect to the endemic epidemiology. RESULTS: Four distinct histological types of follicular cell-derived cancers are recognized, approximately two-thirds are papillary, one-third is follicular, some are oxyphilic cancers and the anaplastic type has become rare lately. The first three types are summed up as differentiated thyroid carcinomas (DTCs). MTC is rare and constitutes 6–7 % of thyroid cancers, of which approximately 75 % are sporadic and 25 % are hereditary. There are no prospective, randomised trials to determine the "optimal treatment" of the various thyroid carcinomas. The "failed TNM classification" in its sixth edition again demolished studies over a longer period, as the fifth and sixth editions were only five years apart and classification does not match. At least in endemic areas surgery should be more radical, as tumour biology seems to be more aggressive and the patients are mainly in the higher risk groups. Therefore total thyroidectomy is the operation of choice for pre- or intraoperatively diagnosed DTCs and MTCs. Less than radical surgery should only be performed for tumours smaller than 10 mm without obvious multicentricity. Central cervical lymph node dissection is mandatory in all operations with pre- or intraoperatively determined cancer. If there is evidence of clinical or pathological central lymph node metastases, an uni- or bilateral neck dissection should be accomplished. Only in patients with occult or incidentally found papillary carcinomas of less than 10 mm completion thyroidectomy and lymph node dissection can be omitted. CONCLUSIONS: As there are no controlled randomized studies, developing guidelines is difficult, especially as data from other parts of the world do not necessarily apply for endemic regions, such as Austria. It is generally agreed that patients with DTC and MTC should be treated by total thyroidectomy with adequate lymph node dissection. Patients can usually be discharged after 2 or 3 days after these procedures, and morbidity for RLNP and postoperative hypoparathyroidism is low when thyroidectomy is performed by an experienced thyroid surgeon. As age >45 years and increasing tumour size predict poor prognosis in DTCs, new means of diagnosis for earlier treatment are therefore necessary. Hereditary MTCs should only be treated in multidisciplinary study groups according to their genetic risk.