NEW YORK--Cancer of the thyroid, a highly treatable disease, is often overlooked in its earliest stages and, once diagnosed, may be treated too aggressively. In an effort to address these issues and to standardize treatment, the American Association of Clinical Endocrinologists (AACE) has published new guidelines for the management of thyroid carcinoma.
At a press briefing, Ian D. Hay, MD, professor of medicine, Mayo Medical School, and co-chair of the AACE Thyroid Cancer Guidelines Task Force, said that the guidelines are intended to resolve current controversy over the diagnosis and treatment of the disease, with the result that "all patients will receive high-quality, cost-effective care."
The incidence of undiagnosed thyroid malignancies may be as high as 3 million, said Stanley Feld, MD, past president of AACE and co-chair of the guidelines task force. Because thyroid cancer is asymp-tomatic, the first sign, a suspicious swelling, is usually noted either by a physician in the course of a routine physical examination or by a patient.
The AACE has recently developed a simple self-examination procedure that it hopes will increase awareness of the disease.
Dr. Feld, clinical associate professor of medicine, University of Texas Southwestern Medical School, Dallas, said that clinical endocrinologists are uniquely qualified to diagnose the disease and to coordinate comprehensive care.
The guidelines are intended to avoid overly aggressive treatment of patients who are not at risk for recurrence while ensuring adequate monitoring and appropriate adjuvant therapy for those who are at risk.
Diagnosis, according to the new guidelines, should be through fine-needle aspiration (FNA) biopsy, which Dr. Feld termed "the gold standard, the most effective method available for distinguishing between benign and malignant thyroid nodules." FNA is most effective in diagnosing papillary thyroid carcinoma, by far the most common type.
The guidelines state that the diagnosis should be verified by histologic examination after surgical excision of affected tissues. Prognosis varies with tumor type; differentiated tumors (papillary and follicular) are highly curable while the less common poorly differentiated tumors (medullary and anaplastic) are more likely to be aggressive and metastatic.
|The AACE has developed an instruction card for performing the neck
check exam. A sample copy and information about bulk orders can be
obtained by sending a self-addressed, stamped envelope to The American
Association of Clinical Endocrinologists, c/o Thyroid Awareness Month,
P.O. Box 1512, Radio City Station, New York, NY 10101-1512.
For more information about the neck check or to download the clinical guidelines, contact the AACE web site at www.aace.com.
Initial treatment is usually surgical, with near-total thyroidectomy the preferred approach in most instances. In this procedure, the lobe containing the dominant tumor mass is removed completely; most of the contralateral lobe is removed, with only a minute amount left in place to preserve the vascular supply to the parathyroid glands. Dr. Hay said that radical neck dissection is now considered overly aggressive in most cases.
Postoperatively, all patients receive daily thyroid hormone replacement for the rest of their lives. For the majority, this is sufficient, though periodic monitoring of TSH levels is essential. For patients at risk for recurrence, adjuvant therapy is recommended.
Said Dr. Hay, "It is now possible to predict risk of recurrence with a high degree of accuracy, employing circulating tumor markers (analogous to PSA) and thyroid scans, with the result that aggressive treatment can be reserved for those who really need it."
Nonradioactive imaging techniques, including ultrasound, are increasingly used for risk assessment, he added.
Patients must be followed precisely and diligently, and for that reason, Dr. Hay stressed the central role of the endocrinologist in coordinating care. "Risk assessment and follow-up should be performed by a clinical endocrinologist who is trained to monitor thyroid hormone levels, deliver radioiodine (RAI), and test for markers," he said.
Options for adjuvant therapy include thyroid suppressive therapy with levothy-roxine and remnant ablation with RAI. In the past, Dr. Hay said, RAI was overused and excessively high doses were given. "RAI should not be used routinely, as it could have long-term negative consequences," he said. External irradiation is used only in rare cases.
Chemotherapy, either mono- or combination therapy, depending on the tumor type, is restricted to patients with unresectable tumors who are unresponsive to RAI and for whom external irradiation is not possible or not effective.
With publication of the AACE guidelines, Dr. Hay said, "we hope to eliminate overaggressive treatment for the majority of patients and avoid inadequate therapy for the minority who are at risk for recurrence." The guidelines have been mailed to 150,000 physicians in the United States.