Radioiodine remnant ablation
Many patients with FCDC receive RAI to ablate residual thyroid tissue postoperatively {RRA}. RRA is defined as "the destruction of residual macroscopically normal thyroid tissue after surgical thyroidectomy." RRA is used as an adjunct to surgical treatment when the primary FCDC has been completely resected. This technique is contrasted with RAI therapy, in which larger doses of I are administered in an attempt to destroy persistent neck disease or distant metastatic lesions.
External irradiation
External irradiation is rarely used as adjunctive therapy in the initial management of patients with FCDC. It may be beneficial, however, in patients with poorly differentiated {higher histologic grade} tumors that do not concentrate RAI. It also may be considered in the postoperative management of patients with FCDC who have gross evidence of local invasion and who are presumed to have microscopic residual disease after primary surgical treatment.
Long-term follow-up-
Diagnostic scanning
For whole-body scanning with Radioactive iodine, an increased serum TSH level { generally >25microIU/mL} is necessary to thyroid cells to accumulate the radio-iodine. This state is usually accomplished by the withdrawal of thyroid hormone therapy. Newly advocated recombinant human TSH does not not require withdrawal of thyroid hormone.
Thyroglobulin
Thyroid tissue is the only source of circulating Tg. Serum Tg levels may be high in thyrotoxicosis, thyroiditis, iodine deficiency, and benign thyroid adenomas as well as in thyroid cancer. Tg is a highly specific tumor marker for differentiated thyroid cancer and has a pivotal role in follow-up of patients with such cancers. After thyroidectomy and successful radioiodine ablation, serum Tg should be undetectable {generally, <2 ng/ mL). After a unilateral lobectomy, serum Tg is usually less than 10 mg/mL during thyroid hormone therapy in the absence of metastatic disease.
Reference
1. Mazzeferri EL, Massoll N. Management of papillary and follicular (differentiated) thyroid cancer: New paradigms
using recombinant human thyropin. Endocrine-Related cancer (2002) 9 227-247
2. Alam MN et al. Spectrum of thyroid disorders in IPGMR, Dhaka.Bangladesh J Medicine 1995; 6: 53-58
3. MCE {American Association of clinical Endocrinologist) guidelines. Thyroid Carcinoma guidelines, Endocr Pract. 2001 ;7 {No.3)
4. Shaheen 0, Thyroid neoplasm Scott-Browns otolaryngology, 5th ed. Alan G Kerr. 1987, p. 301-14.
5. NCCN {National comprehensive cancer network), Practice Guidelines in Oncology-v.1.2002, Thyroid Carcinoma
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