My mother-in-law had her thyroid removed because of cancer and was given iodine treatment. She had this done about a year or two ago. Now she is experiencing difficulty swallowing, breathing and sleeping. She is also hoarse. The doctor also said she has partial paralysis of her vocal cords. What do you think the problem is? She's been in pain for the last four months and the pain is only increasing.

R.M.

This is a tough question to answer, because much depends upon the exact timing of her symptoms. I am going to assume that she initially did well after surgery and had none of the symptoms you mention (difficulty with sleep, breathing and swallowing as well as hoarseness) until recently. If this assumption is correct, then the recent onset of these problems is extremely worrisome, since they suggest that her cancer has recurred. Consequently, she REALLY needs to bring these problems to the attention of her doctor, if she has not already done so.

A discussion of thyroid anatomy will be useful, because you will then appreciate how a thyroid tumor could cause these symptoms. As you and your mother-in-law undoubtedly know, the thyroid lives in the center of the neck, right above the breast bone. Take a finger and "walk it" up the breast bone, until you reach the soft part of the neck. To either side of your fingertip, you will feel a very large muscle attaching to the collar bones. Press between these two muscles, and you will feel something hard -- you are feeling the cartilage of the voice box (larynx) or windpipe (trachea).

The thyroid gland is positioned immediately in front of the trachea, just below the larynx. The thyroid wraps around the front and sides of the trachea. The esophagus runs behind the trachea. To either side of the esophagus and trachea run the recurrent laryngeal nerves (left and right), which "work" the vocal cords.

Thyroid enlargement (goiter) and thyroid tumors (malignant or benign) can cause breathing problems if the trachea is compressed, and swallowing problems if the esophagus is compressed. Both problems are typically worse when the patient is on her back; this may explain your mother-in-law's difficulty sleeping. If the tumor damages one of the recurrent laryngeal nerves, vocal cord paralysis may result, and this can cause hoarseness. Surgery to remove the thyroid (thyroidectomy) can also result in recurrent laryngeal nerve injury, so it is important to determine whether your mother-in-law's hoarseness and vocal cord paralysis are new or old problems.

I am also going to assume that your mother-in-law's pain is in her neck, near the thyroidectomy scar. If so, then this too is worrisome for cancer recurrence. Cancers invade and destroy neighboring tissues. If sensory nerves are invaded, pain results. There are many possible explanations for throat pain, but given your mother-in-law's history and her other symptoms, cancer recurrence is the most concerning possibility.

How can this problem be investigated? Your mother-in-law's doctor may decide to order a thyroid scan; if she had a complete thyroidectomy, the scan should find no remaining thyroid tissue. Alternatively, her doctor may wish to order a CT or MRI scan of her neck.

If she does have recurrent cancer, what can be done about it? In many cases, it is best to surgically remove as much of the new tumor as possible. Afterwards, she could probably receive more radioactive iodine treatment to "mop up" residual disease. (That was the purpose of her first iodine treatment, by the way -- to eradicate microscopic amounts of residual cancer. Thyroid cells actively concentrate iodine, much more so than any other tissue. Radioactive iodine is thus a very effective means of targeting radiation therapy to the tissue that needs it the most.)

Left unchecked, recurrent cancer in this region will ultimately cause life-threatening problems such as esophageal perforation and airway obstruction. Once again: Please encourage your mother-in-law to talk to her doctor at once.