Thyroid Cancer

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Thyroid Cancer (read reviews on external beam and iodine therapy)

As noted below the treatment for thyroid cancer is surgery often followed by radioactive Iodine. For papillary or follicular cancer, a scanning dose (1-2mCi of I-131) is performed once the TSH is high (> 30-50 or using thyrogen.) If there is residual disease in the neck an ablative dose is used (e.g. 30 mCi.) the patients is then rescanned in 6-12 months and if mets are found then a therapeutic dose (e.g. 100-200 mCi is used) see NCI, NCCN Guidelines and review article. Post-operative external beam is used in more advanced cases particularly if the tumor takes up iodine poorly (see NCCN1). Radiation (plus chemotherapy) is used for anaplastic carcinomas (see NCCN2 and here and here).

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CT Scan through the neck of a patient with a large thyoid cancer, pushing the trachea towards the right side

Semin Surg Oncol 1999 Jan-Feb;16(1):42-9

External-beam radiation therapy in the treatment of differentiated thyroid cancer.

Brierley The role of external-beam radiation therapy (EBRT) in differentiated thyroid cancer is reviewed. In the presence of gross residual disease after attempted surgical excision, retrospective series have reported local control is possible with EBRT. If, in addition to Iodine-131 (I131), there is a role for adjuvant EBRT in differentiated thyroid cancer, it would be only in patients in whom there is a high risk of relapse in the thyroid bed. Evidence is presented that suggests that EBRT can improve the local relapse-free rate in selected patients (over the age of 45, with microscopic residual disease or extensive extrathyroid invasion). For patients with recurrence in the thyroid bed, EBRT can be given in addition to surgery and I131. In bone metastases that are demonstrable radiographically, I131 therapy is often unsuccessful and EBRT also should be given. EBRT has acceptable acute toxicity and rarely produces serious long-term complications.

Otolaryngol Clin North Am 1990 Jun;23(3):509-21

Radioiodine and radiotherapy in the management of thyroid cancers.

Simpson Radioiodine is an important adjuvant treatment in the management of resectable papillary and follicular thyroid cancers in all patients except those with the best prognostic features. External radiation is also an important adjuvant therapy in these patients, especially those with tumors that extend beyond the thyroid gland and invade the trachea, esophagus, nerves, and blood vessels; it is especially important in treating patients whose tumors do not concentrate radioiodine. Radioiodine may be curative in patients with microscopic distant metastases demonstrated by radioiodine scanning. Even unresectable primary papillary and follicular cancers may be eradicated by combined therapy with radioiodine and radiotherapy. Radioiodine plays no significant role in the treatment of medullary or anaplastic thyroid cancers, but external radiation may eradicate microscopic thyroid bed or nodal disease when persistent disease is indicated by elevated calcitonin levels in medullary thyroid cancer patients. Anaplastic thyroid cancers are usually unresectable and are not eradicated by conventional radiotherapy or by any of the novel radiation techniques, with or without chemotherapy. In all types of thyroid cancer, external radiotherapy may produce beneficial palliative results in patients with distant metastases, but the use of radioiodine should always be explored in papillary and follicular thyroid cancer patients.