REVIEWPalliation of advanced thyroid malignancies
Introduction
In the year 2007, an estimated 33,550 new cases of thyroid cancer will be diagnosed in the United States. While the overall 5-year survival for thyroid cancer is excellent (over 96%), approximately 1500 individuals in the US will die of the disease in 2007 [1].
Patients with advanced cancer frequently develop multiple symptoms for a period of weeks to months before death. Common physical symptoms include pain, weakness, fatigue, nausea and vomiting, shortness of breath, and cachexia-anorexia. Neuropsychiatric symptoms include depression, anxiety, insomnia, and delirium [2].
Due to the anatomical location of the thyroid gland, advanced thyroid malignancies frequently impinge upon or invade important structures in the neck such as the trachea, esophagus, major blood vessels, and nerves, causing distressing and life-threatening symptoms such as dyspnea, dysphagia, and hemoptysis. Cancers that metastasize to distant sites such as the lungs, bone, and liver can cause pain and organ dysfunction. As a neuroendocrine tumor, medullary thyroid cancer can also cause symptoms such as diarrhea and flushing secondary to tumor secretion of various bioactive amines and peptides. These symptoms are often a source of great discomfort and distress for the patient with advanced thyroid cancer, as well as his or her family, and represent an important challenge for the treating physician. This article will discuss palliative treatments, including surgery, radioactive iodine (RAI), external beam radiation, and chemotherapy, for a variety of symptoms that arise in patients with advanced thyroid cancer.
Section snippets
Palliative treatment of well-differentiated thyroid cancer
The well-differentiated—i.e., papillary and follicular—thyroid carcinomas (WDTCs) are typically indolent, with excellent long-term survival rates when treated with surgery and RAI [3]. However, a subset of tumors exhibit aggressive behavior. Advanced malignancies with extensive local invasion or distant metastases are often incurable. For these patients, the goal of therapy is to extend life and palliate symptoms.
Palliative treatment of Hürthle cell thyroid cancer
Hürthle cell carcinomas (HCCs), first described in 1928 by Ewing [52], account for approximately 6% of all well-differentiated thyroid cancers [53], and are classified by the World Health Organization as a variant of follicular thyroid cancer [54]. Hürthle cells, also known as oxophylic cells, oncocytic cells, and Askanazy cells, are characterized by abundant granular pink cytoplasm containing many mitochondria. Like FTCs, HCCs are differentiated from adenomas on the basis of capsular or
Palliative treatment of medullary thyroid cancer
Medullary thyroid carcinoma (MTC), which arises from calcitonin-secreting parafollicular cells of the thyroid gland, accounts for 2–5% of all cases of thyroid cancer in the US [70]. The average 5-year survival for MTC (83%) is lower than for papillary and follicular thyroid cancer (90–94%) [71], [72]. The natural history of MTC is significant for early metastasis to local and regional lymph nodes. In advanced cases MTC can invade local structures such as the trachea and jugular vein, and
Palliative treatment of anaplastic thyroid cancer
Anaplastic thyroid carcinoma (ATC) is one of the most lethal malignancies, with a median survival of only 4–12 months from the time of diagnosis [111]. Patients typically present with a rapidly enlarging neck mass, and symptoms related to mechanical compression, such as dyspnea, stridor, dysphagia, hoarseness, and pain, are common. Distant metastases are evident in half of patients at presentation, and another 25% develop metastases during the course of the illness. As with WDTC, the lung is
Palliative treatment thyroid lymphoma
Primary thyroid lymphoma (PTL) is an uncommon malignancy. It accounts for less than 4% of all extra-nodal non-Hodgkin's lymphomas and 5% of thyroid malignancies [143], [144]. PTLs typically occur in middle-to older-aged women and frequently arise in the setting of autoimmune thyroiditis [145].
As in ATC, the most common symptom in PTL is a rapidly enlarging neck mass. Symptoms of airway or esophageal obstruction develop in 30% of patients [146]. These symptoms, including dyspnea, dysphagia,
Conclusions
The majority of thyroid cancers are slow growing and have an excellent prognosis after surgical and medical therapy. However, a subset of thyroid cancers do not follow an indolent course, and exhibit aggressive behavior. Advanced thyroid malignancies can cause distressing and life-threatening symptoms by local invasion, growth of distant metastases, and tumor production of hormones. A variety of treatments are available for the palliative care of patients with incurable thyroid cancer. Novel
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