Thyroid Cancer

    Types of Thyroid Cancer

   The common types of cancer respond well to treatment. Except for the
   rare medullary thyroid cancer, the occurrence of malignancy among
   members of the same family is extremely unusual. Patients with
   medullary cancer should ensure that family members are appropriately
   tested by both clinical and biochemical tests at an early stage even
   when no thyroid nodules are detectable. Medullary cancer may also be
   associated with simultaneous involvement of other endocrine glands
   such as the pituitary, adrenal, pancreas and parathyroid glands. Such
   involvement is known as multiple endocrine neoplasia syndrome.

    Radiation Exposure

   Previous exposure to head and neck irradiation in childhood,
   adolescence or even adulthood has been recognized as an important
   contributing factor for the development of thyroid cancer. Years ago,
   patients received x-ray treatments for acne, skin problems of the
   face, tuberculosis in the neck, fungus diseases of the scalp, blood
   vessel tumors of the face, enlarged thymus, tonsillitis, sore throats,
   chronic coughs, and even excess facial hair. Such therapy is NO longer
   performed for these problems because it became recognized that the
   thyroid gland is particularly sensitive to the effects of radiation
   resulting in thyroid tumors with a 30% risk for cancer. In addition,
   patients who require radiation for the treatment of certain types of
   cancer in or near the head and neck area may also have an increased
   risk for the development of thyroid nodules and thyroid cancer. If you
   have had radiation for any such problems, then consultation with your
   physician would be appropriate to ensure that your thyroid gland is
   functioning normally and does not have any nodules.

    Treatment

   To confirm whether a thyroid nodule is present, thyroid scanning and
   ultrasound imaging procedures are used. However, a fine needle
   aspiration biopsy is the BEST diagnostic measure by far to detect
   which nodules will require surgical intervention because of overt or
   suspect cancer and exclude those which do not. The most effective form
   of initial thyroid cancer therapy is surgery (see Health Guide #11 -
   Surgical Treatment of Thyroid Disease). Because of the excellent
   outlook for most thyroid cancers, some surgeons feel that it is
   sufficient to remove only a portion of the gland. However, there is a
   growing body of evidence based upon long term follow-up which
   indicates that it is worthwhile to remove as much of the thyroid gland
   as is safe. This more aggressive approach will avoid recurrences and
   optimize subsequent non-surgical measures such as radioactive iodine
   therapy. Although a total thyroidectomy slightly increases the risk
   for possible deficiency in calcium by the inadvertent removal of
   nearby parathyroid glands, this risk should be minimized when the
   thyroid cancer surgery is performed by an experienced surgeon. The
   potential for vocal cord damage is also extremely rare in experienced
   hands.

   In about 30% of patients, the cancer may spread from the thyroid gland to
   other areas.
   It may involve the lymph glands nearby in the neck. If this occurs,
   the lymph glands should be removed by an operation called a neck
   dissection. The extent of the removal depends in part on how many lymph
   nodes appear affected by the cancer. Usually this can be achieved
   through cosmetically satisfactory incisions. Occasionally, the incision
   may have to be  elongated. Apart from some transient swelling of the face,
   the removal of such lymph glands results in NO serious bodily
   deprivation or dysfunction.

    Radioactive Iodine Therapy

   Depending on the findings at the time of surgery, radioactive iodine
   may be considered post-operatively. Radioactive iodine is administered
   in either a capsule or liquid form usually 6 weeks after completing
   the necessary surgery. In order for the radioactive iodine to work,
   thyroid replacement (tablets) are withheld during this time.
   Unfortunately, the patient must endure the consequences of an
   underactive thyroid which may include fatigue, muscle cramps,
   puffiness and constipation. However, knowing it is absolutely
   necessary and that thyroid replacement will begin at the completion of
   treatment helps patients deal with this consequence. In research
   studies, patients receiving human TSH injections have not had to stop
   their thyroid tablets. Hopefully, this material will be available for
   general clinical use in the near future.

   Radioactive iodine therapy is simple but depending upon dosage may
   require isolation in a hospital room for several days. Although
   transient neck discomfort, decreased saliva formation and alteration
   in taste may rarely occur, there are usually no significant side
   effects. Occasionally this treatment is repeated if residual or
   recurrent thyroid cancer is detected. When radioactive iodine is
   administered at well established dosage and treatment intervals, over
   50 years of experience has indicated that it is relatively safe with
   few serious early or late side effects.

    External Radiation Therapy

   X-ray radiation from an external source by "cobalt beam" is
   rarely necessary but could be recommended when the thyroid cancer
   cannot be completely removed. External radiation is administered over
   a 4 to 6 week interval in small divided doses to the neck region and
   may induce a secondary skin reaction due to the formation of small
   blood vessels and pigment darkening of the skin. However, this does
   not invariably occur.

    Post-Treatment Check-Ups

   Following surgery and radioactive iodine therapy, thyroid hormone
   pills are prescribed. Thyroid hormone not only ensures proper
   metabolism but suppresses the pituitary hormone, thyrotropin (TSH)
   which can stimulate thyroid cancers to grow. Unlike patients with an
   underactive thyroid, thyroid cancer patients are treated with dosages
   sufficient to maintain the serum TSH level below normal to prevent
   further growth of the cancer. The level of thyroid function is checked
   periodically by both clinical examination and laboratory tests.
   Thyroid cancer patients are examined at regular 6 to 12 month
   intervals to ensure that there is no evidence of recurrent cancer.
   Measurement of serum thyroglobulin (the precursor of thyroid hormone)
   is the single best test to determine whether recurrences have
   occurred. Neck ultrasounds and chest x-rays may also be required to
   ensure that the cancer has not persisted or recurred.

    Summary

   For the commonest forms of papillary and papillary-follicular thyroid
   cancer the 5 and 10 year survival rates are IN EXCESS OF 95%. The risk
   for recurrence is higher in patients over the age of 45 or if the
   thyroid cancer has extended outside of the thyroid gland at the time
   of the original diagnosis. However, early detection and treatment
   often averts such consequences.

   Patients usually have questions regarding thyroid cancer. Here are
   some of them. If you have a different question, you might write to the
   Thyroid Foundation of Canada and answers may be published in the
   Thyrobulletin by a consultant doctor.

    QUESTIONS AND ANSWERS

    1. QUESTION: Does smoking or drinking cause thyroid cancer?

       ANSWER: Smoking and drinking are not related to thyroid cancer.
       Such habits of course are better avoided for overall good health
       but they neither cause nor aggravate the course of thyroid gland
       malignancy.

    2. QUESTION: Does thyroid cancer spread throughout the body and how
       can you tell if this is so?

       ANSWER: Thyroid cancer rarely spreads throughout the body. Most
       thyroid cancers are cured by the initial operation. Although
       thyroid cancer may extend to lymph glands in the neck, the removal
       of these lymph glands is usually quite feasible and curative.
       Infrequently cancers do spread to lung and bone and can be
       detected by x-ray and scanning imaging procedures. Such a
       situation requires treatment by radioactive iodine or other x-ray
       therapy procedures and occasionally surgical removal. For the rare
       but more aggressive types of cancer, treatment with chemotherapy
       and x-ray therapy may be recommended.

    3. QUESTION: How likely are my chances of dying of thyroid cancer
       even with all this treatment?

       ANSWER: Other than skin cancer, the most common types of thyroid
       cancer have the best longterm outcome when promptly treated
       compared to all other types of cancer. Almost all patients are
       totally cured by treatment.

    4. QUESTION: How is thyroid cancer detected?

       ANSWER: Thyroid cancer is frequently detected by the patient
       becoming aware of a lump in the neck. Half such cases are detected
       by a physician during a routine physical examination for an
       unrelated problem. Thyroid cancer does not cause pain and rarely
       produces symptoms. Virtually all patients with thyroid cancer have
       normal metabolism and thyroid tests.

    5. QUESTION: What are the side effects of treatment? Will I lose my
       voice or have a large scar?

       ANSWER: The usual treatment of thyroid cancer involves the removal
       of at least a portion or all of the thyroid gland through a small
       neck incision. It is infrequent for patients to have any problem
       with a voice disorder or calcium imbalance as a consequence of the
       surgery. The removal of lymph glands may require a larger
       incision, but this is usually low in the neck and is still
       compatible with a good cosmetic result.

    6. QUESTION: What can I do to ensure that I have the very best result
       of treatment for my thyroid cancer?

       ANSWER: It is important that nodules in the thyroid gland or in
       the neck area be appropriately diagnosed at an early stage. You
       should see your family doctor who will assess the situation and
       most likely refer you to the appropriate specialist to confirm the
       diagnosis and administer the correct treatment. However, in
       contrast to many other cancers, early detection and treatment
       almost always results in a complete eradication and cure!

    7. QUESTION: Will I have to stop my thyroid tablets if radioactive
       iodine is being given?

       ANSWER: Yes, for 6 weeks. The only way the radioactive iodine can
       "get into" the thyroid and work is if your TSH level
       becomes elevated. This will occur when you stop your thyroid
       hormone. Unfortunately, during this time you will likely
       experience the effects of an underactive thyroid which may include
       fatigue, muscle cramps, puffiness and constipation. Research
       trials using human TSH injections look promising. Hopefully, once
       this agent is available, patients will be able to undergo
       radioactive iodine treatment without having to stop their thyroid
       replacement.