Well-differentiated thyroid cancer is something of an anomaly in the field of oncology for two primary reasons. First, the team of physicians who manage the patient consists primarily of endocrinologists, endocrine surgeons, and nuclear medicine physicians instead of medical oncologists, surgical oncologists, and radiation oncologists. Second, there is an extremely high rate of cure with remarkable 10- and 20-year survival rates due to the indolent nature of the tumor, even in the setting of lymph node metastases.
Dr. Angelos presents a thoughtful review of well-differentiated thyroid cancer, highlighting key issues in diagnostic evaluation, surgical treatment, and postoperative adjuvant radioactive iodine(Drug information on iodine). He discusses the controversial areas associated with treatment of the diseaseie, the extent of surgery and the management of patients with elevated thyroglobulin as the only indication of recurrent disease.
The benefits and limitations of the diagnostic studies available to evaluate a thyroid nodule are also reviewed in this article. Although fine-needle aspiration (FNA) examined by an experienced cytologist is the key study that determines appropriate surgical management, ultrasound and nuclear medicine scans provide specific benefits in certain clinical situations.
The principle benefit of ultrasound is in assessing the size of lesions and evaluating for other occult thyroid nodules, as pointed out by the author. The current recommendation is that only thyroid nodules measuring > 1 cm in two dimensions warrant biopsy. Ultrasound may identify other nonpalpable lesions that are large enough to be assessed by FNA. A second use of ultrasound is to guide the FNA. As pointed out by the author, nonpalpable lesions are increasingly being identified by other diagnostic tests, and ultrasound is essential in guiding the biopsy of these lesions. However, ultrasound may be used even for palpable nodules that are nondiagnostic on initial FNA because of bloody aspirate or minimal material. Ultrasound-guided biopsies allow placement of the needle into viable nonnecrotic sections of the nodule.
Nuclear medicine scans generally provide little additional information because even though virtually all malignant nodules are cold on iodine scan, the majority (80% to 83%) of cold nodules are still benign. The most important use of iodine-uptake scanning in patients with multiple nodules is in identifying hypofunctional lesions that should be studied with FNA.
Issues Regarding Cytologic Diagnosis