tailieunhanh - Chapter 084. Head and Neck Cancer (Part 1)

Harrison's Internal Medicine Chapter 84. Head and Neck Cancer Head and Neck Cancer: Introduction Epithelial carcinomas of the head and neck arise from the mucosal surfaces in the head and neck area and typically are squamous cell in origin. This category includes tumors of the paranasal sinuses, the oral cavity, and the nasopharynx, oropharynx, hypopharynx, and larynx. Tumors of the salivary glands differ from the more common carcinomas of the head and neck in etiology, histopathology, clinical presentation, and therapy. Thyroid malignancies are described in Chap. 335. Incidence and Epidemiology The number of new cases of head and neck cancers in. | Chapter 084. Head and Neck Cancer Part 1 Harrison s Internal Medicine Chapter 84. Head and Neck Cancer Head and Neck Cancer Introduction Epithelial carcinomas of the head and neck arise from the mucosal surfaces in the head and neck area and typically are squamous cell in origin. This category includes tumors of the paranasal sinuses the oral cavity and the nasopharynx oropharynx hypopharynx and larynx. Tumors of the salivary glands differ from the more common carcinomas of the head and neck in etiology histopathology clinical presentation and therapy. Thyroid malignancies are described in Chap. 335. Incidence and Epidemiology The number of new cases of head and neck cancers in the United States was 40 500 in 2006 accounting for about 3 of adult malignancies. The worldwide incidence exceeds half a million cases annually. In North America and Europe the tumors usually arise from the oral cavity oropharynx or larynx whereas nasopharyngeal cancer is more common in the Mediterranean countries and in the Far East. Etiology and Genetics Alcohol and tobacco use are the most common risk factors for head and neck cancer in the United States. Smokeless tobacco is an etiologic agent for oral cancers. Other potential carcinogens include marijuana and occupational exposures such as nickel refining exposure to textile fibers and woodworking. Dietary factors may contribute. The incidence of head and neck cancer is highest in people with the lowest consumption of fruits and vegetables. Certain vitamins including carotenoids may be protective if included in a balanced diet. Supplements of retinoids such as m-retinoic acid have not been shown to prevent head and neck cancers or lung cancer and may increase the risk in active smokers. Some head and neck cancers may have a viral etiology. The DNA of human papillomavirus HPV has been detected in the tissue of oral and tonsil cancers and may predispose to oral and tonsillar cancer in the absence of tobacco and alcohol use. These .

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