Thyroid Cancer



Most thyroid cancers are slow growing tumors and generally carry a favorable prognosis.


However, some thyroid cancers are quite aggressive and carry a poor prognosis.


One dangerously aggressive form of thyroid cancer is called medullary thyroid cancer which is usually familial. Gene testing (a blood test) is now available to family members of a patient with medullary thyroid cancer who are also at risk for the development of this cancer.



Diagnosis of Thyroid Cancer



A thyroid cancer is usually discovered as a result of a fine needle aspiration biopsy or the surgical biopsy of a thyroid nodule.



Treatment of Thyroid Cancer



Once thyroid cancer has been diagnosed, thyroid surgery is performed to remove all the thyroid tissue, followed in many cases by a dose of radioactive iodine which serves two purposes:


A. It destroys any remaining thyroid cells, cancerous as well as non-cancerous.


B. Once all the thyroid cells are destroyed, the body can no longer produce a substance called thyroglobulin (which is normally produced only by the thyroid tissue).



Follow-Up for Thyroid Cancer



Thus, measuring serum thyroglobulin becomes an excellent tool to detect the recurrence of thyroid cancer, indicated by an increase in thyroglobulin level.  


Follow-up of most thyroid cancer patients includes:


1. Large doses of thyroid hormone to suppress serum TSH (thyroid stimulating hormone ) to prevent recurrence of the cancer.


2.  Measuring serum thyroglobulin on a yearly basis to detect any recurrence of the thyroid cancer.


3. Total body scan on a yearly basis to detect any recurrence of the thyroid cancer.



 Withdrawal Scan VS Thyrogen Scan



In the past, we had to stop a patient's thyroid hormone pills for several weeks before doing the whole body scan. This is called the Withdrawal Scan.


The patient had to got through a miserable period of several weeks of hypothyroid symptoms.


However, in the last few years, a new way of doing the whole body scan has developed in which the patient does not have to be off the thyroid hormone pills.


This is called the Thyrogen Scan.



Thyrogen Scan



Thyrogen is a synthetic form of TSH (thyroid stimulating hormone). It is given in the form of an intramuscular injection on two consecutive days.


Radioactive iodine is given 24 hours after the last injection of Thyrogen and whole body scan is obtained 48 hours later.


Thyrogen injections are very expensive.





Thyrogen injections can cause side-effects such as headache, Flu like symptoms, breathing difficulties and even heart attacks and deaths have been reported.


The physician administering Thyrogen injections (usually a radiologist) should discuss potential side-effects of Thyrogen with the patient before giving Thyrogen.    




This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, photoEndocrinology and Metabolism.



Dr. Zaidi is a former assistant Clinical Professor of Medicine at UCLA and Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.



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