[Papillary and follicular cancers of the thyroid]

Abstract

MANAGEMENT STRATEGIES: Management of papillary and follicular cancer of the thyroid varies somewhat between centers because of the generally good prognosis and the absence of well-controlled therapeutic trials. The internationally recognized TNM system is widely used to modulate treatment and follow-up to the individual situation.

Primary treatment: Surgery is indicated in well-differentiated thyroid cancer. Total thyroidectomy is required for clinically patent tumors (> or = 1 cm) and small tumors (< 1 cm) recognized prior to surgery. For small tumors found at histology examination, reoperation is discussed in terms of prognosis. Post-operative 131-iodine is indicated when surgical resection is incomplete or in case of unfavorable prognosis. External radiotherapy is currently reserved for exceptional cases with unremoved tumoral tissue unresponsive to 131-iodine.

Follow-up: All operated patients are given L-thyroxine to achieve euthyroidism and low TSH levels (< 0.1 microU/ml). Early detection of relapse is based on combined thyroglobulin assay and whole body 131-iodine scintigraphy. Both are performed during the first year of follow-up after a period of thyroid hormone withdrawal. Human recombinant TSH will soon be available allowing selection of patients with a detectable thyroglobulin level after stimulation; these patients should have a 131-iodine scintigram. If thyroglobulin remains undetectable during L-thyroxine treatment, an annual dosage is indicated and other exams are unwarranted.

Relapse: Surgery is indicated in case of small areas of active recurrent tumoral tissue in a cervical location. If a high-sensitivity scintigram does not show iodine uptake, the surgical procedure is completed by radiotherapy or possibly chemotherapy with doxorubicin. Small recurrent tumors in other areas respond to 131-iodine (3.7 GBq). Surgery, 131-iodine and radiotherapy are usually indicated for large ectopic recurrences. Chemotherapy is ineffective.

Current protocols: Standard primary therapy generally provides cure and most patients are followed by annual thyroglobulin and TSH assays. Other explorations beginning with a whole-body 131-scintigram may be indicated in selected patients.