Managing Thyroid Cancer
Each year in the United States, thyroid cancer represents a minority of new cancer diagnoses (approximately 1 percent). However, the rate at which the disease is being diagnosed seems to be on the rise.
The reason for that rising incidence is "pretty well understood," says Robert Block, MD, one of eight otolaryngologists at Central Coast Head and Neck Surgeons. Dr. Block, who completed residencies in both otolaryngology and facial plastic and reconstructive surgery at UCLA, says higher rates of thyroid cancer are being seen because of the use of ultrasounds with greater accuracy, which translates into earlier diagnosis.
Vital to normal growth and development, the thyroid gland is a small butterfly-shaped endocrine gland (a gland that controls hormone secretion into the bloodstream) that sits in front of the trachea (windpipe) just below the Adam's apple. Through its production of thyroid hormones, the thyroid gland regulates metabolic functions such as body temperature, blood pressure, oxygen utilization and calorie consumption.
Kenneth Nowak, MD, also a board-certified otolaryngologist with Central Coast Head and Neck Surgeons, completed his residency in otolaryngology at Stanford University Medical Center. Dr. Nowak points out that thyroid cancer is less common than skin cancer, but agrees that its incidence appears to be on the rise.
"We have more means of detecting cancers earlier, so we may be more efficient at finding them," Nowak explains.
More common in women than in men at a ratio of 3:1, thyroid cancer incidence peaks after age 30. Those who received radiation treatment to the head, neck or chest areas, especially during childhood, or who were exposed to radiation after a nuclear bombing or nuclear power plant accident, have an increased risk for developing the disease. Low-dose exposure from common imaging procedures such as dental x-rays has not been shown to increase the risk of developing thyroid cancer.
Most thyroid cancers develop within thyroid nodules (lumps). Up to 75 percent of the population will develop a thyroid nodule, but the majority (95 to 97 percent) of these nodules are benign. Although causes of most cases of thyroid cancer remain unclear, the most common forms, papillary (80 percent of all thyroid cancers) and follicular (10 percent of cases), are readily curable.
Presenting signs and symptoms of thyroid cancer include a painless thyroid lump (most common symptom), difficulty swallowing due to thyroid gland enlargement, persistent cough, hoarseness and throat or neck pain. Diagnosis is confirmed with an ultrasound-guided fine-needle biopsy. Disease management, which includes removal of the gland (thyroidectomy) is generally handled by an endocrinologist (a physician who specializes in disorders of the endocrine system), a surgeon (usually an otolaryngologist) and a radiologist.
In Block's hands, a total thyroidectomy can take anywhere from 45 minutes to an hour and 15 minutes.
"Patients recover in a week to 10 days," Block says. "Depending on other risk factors such as the patient's age, the size of the cancer and whether or not it has spread to lymph nodes in the neck, more extensive surgery may be required."
Four small glands that sit next to the thyroid gland (parathyroid glands) are responsible for calcium homeostasis and at risk for being jeopardized during thyroidectomy. In an effort to preserve them, a thin rim of thyroid tissue is often left around the parathyroids.
Radioactive Iodine Treatment
To wipe out cancer cells that were left behind during thyroidectomy, radioactive iodine treatment, a "one-shot deal" that is usually given four to six weeks after surgery, Block says, may be instituted.
The use of radioactive iodine in the management of thyroid cancer is predicated on the fact that iodine absorption from the bloodstream is integral to the production of thyroid hormone by the thyroid gland.
Given that most thyroid cancer cells retain the ability to absorb and concentrate iodine, "microscopic thyroid tissue that's left behind will have an affinity for iodine," advises Block. "And the radioactivity will burn it away."
After undergoing thyroidectomy, patients usually require lifelong thyroid hormone replacement. Calcium and thyroid hormone levels are monitored along with levels of thyroglobulin, a protein that's secreted by the thyroid gland and utilized as an indicator of cancer recurrence. Routine head and neck examinations are also performed by the the patient's physician.
Even after thyroidectomy, thyroid cancer may recur. Cancer cells may have spread through blood vessels to other organs and to lymphatic tissue prior to removal of the gland.
"Or there could be spread into adjacent structures that didn't get fully treated," Block explains.
The cure rate for thyroid cancer depends on "cell type, age of the patient, disease stage, the size of the nodule, and whether it's spread to different sites," Block adds. While most thyroid cancers cannot be prevented, "the survival rate is well above 95 percent."
"The most important thing," Nowak emphasizes, "is to have a regular physician who will routinely examine the neck. If an abnormal nodule is felt, that can lead to early diagnosis."