Opzioni di trattamento per il cancro alla tiroide: dalla chirurgia allo iodio radioattivo

Thyroid cancers are classified into four main histological types. Papillary thyroid cancer (PTC): comprises 80-85% of all thyroid cancers. Usually a slowly growing tumour with possible lymph node metastasis but rare distant metastasis, with excellent prognosis. Follicular thyroid cancer (FTC): seen in 10-15%; can metastasise via blood to lungs and bone rather than lymph nodes.

Medullary thyroid cancer (MTC): originates from thyroid gland parafollicular C cells; followed with calcitonin marker. 25% is hereditary (associated with MEN2 syndrome). Anaplastic thyroid cancer: the rarest (1-2%) but most aggressive form; early-stage diagnosis is rare and prognosis is poor.

Regarding surgical scope, important revisions have been made in international guidelines in recent years. For low-risk papillary microcarcinoma cases (<4 cm, single focus, intrathyroid, no lymph node metastasis), active surveillance or lobectomy may be sufficient. In standard-high risk groups total thyroidectomy is preferred and removal of all thyroid tissue is required for radioactive iodine therapy to be planned.

In the presence of cervical lymph node metastasis, therapeutic neck dissection is added. Central compartment dissection (level VI) is applied for suspected or proven central lymph node involvement; lateral neck dissection is performed for clinically positive lateral lymph nodes.

Radioactive iodine (I-131) therapy is applied after total thyroidectomy for differentiated thyroid cancer (papillary, follicular). The target is to ablate remaining thyroid tissue (remnant), treat lymph node and distant metastasis foci and create the possibility of lifelong follow-up with whole-body scintigraphy.

RAI therapy is performed as an inpatient stay; the patient stays in a special radiation isolation room for 2-5 days. TSH stimulation is required before treatment (thyroid hormone withdrawal or recombinant TSH injection). A low-iodine diet is followed after treatment; normal life resumes after special conditions pass.

Thyroxine (levothyroxine) therapy is used after thyroidectomy for both hormonal replacement and TSH suppression purposes. Since TSH stimulates thyroid cancer cell growth, levothyroxine dose is adjusted to suppress TSH level. The suppression target varies based on patient risk class: in low-risk patients TSH can be maintained at the lower limit of normal while in high-risk patients marked suppression is recommended.

Long-term follow-up is conducted with thyroglobulin and anti-thyroglobulin antibody measurements, neck ultrasound and whole-body scintigraphy when required. Thyroglobulin is a tumour marker in papillary and follicular thyroid cancer; its fall to undetectable levels after total thyroidectomy and RAI is a remission indicator.