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Nasopharynx cancer

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Title: Nasopharynx cancer  
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Subject: Cytomegalovirus esophagitis, Simian-T-lymphotropic virus, Epstein–Barr virus nuclear antigen 1, Arbovirus encephalitis, Herpesviral meningitis
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Nasopharynx cancer

Nasopharynx cancer
Classification and external resources
Metastatic nasopharyngeal carcinoma in a lymph node
ICD-10 C11
ICD-9 147
OMIM 161550
DiseasesDB 8814
eMedicine ped/1553
MeSH D009303

Nasopharynx cancer or nasopharyngeal carcinoma (NPC) is the most common cancer originating in the nasopharynx, the uppermost region of the pharynx ("throat"), behind the nose where the nasal passages and auditory tubes join the remainder of the upper respiratory tract. NPC occurs in children and adults. NPC differs significantly from other cancers of the head and neck in its occurrence, causes, clinical behavior, and treatment. It is vastly more common in certain regions of East Asia and Africa than elsewhere, with viral, dietary and genetic factors implicated in its causation. It is most common in males. It is a squamous cell carcinoma or an undifferentiated type. Squamous cells are a flat type of cell found in the skin and the membranes that line some body cavities. Differentiation means how different the cancer cells are from normal cells. Undifferentiated is a word used to describe cells that do not have their mature features or functions.

Symptoms and signs

Cervical lymphadenopathy (disease or swelling of the lymph nodes in the neck) is the initial presentation in many patients, and the diagnosis of NPC is often made by lymph node paraneoplastic syndrome of osteoarthropathy (diseases of joints and bones) may occur with widespread disease.

Causes

Nasopharyngeal carcinoma (NPC) is caused by a combination of factors: viral, environmental influences, and heredity.[1] The viral influence is associated with infection with etiological factors include genetic susceptibility, consumption of food (in particular salted fish)[4] containing carcinogenic volatile nitrosamines.[5]

The association between Epstein-Barr virus and nasopharyngeal carcinoma is unequivocal in World Health Organization (WHO) types II and III tumors but less well-established for WHO type I (WHO-I) NPC, where preliminary evaluation has suggested that human papillomavirus HPV may be associated.[6] EBV DNA was detectable in the blood plasma samples of 96% of patients with non-keratinizing NPC, compared with only 7% in controls.[3] The detection of nuclear antigen associated with Epstein-Barr virus (EBNA) and viral DNA in NPC type 2 and 3, has revealed that EBV can infect epithelial cells and is associated with their transformation. The etiology of NPC (particularly the endemic form) seems to follow a multi-step process, in which EBV, ethnic background, and environmental carcinogens all seem to play an important role. More importantly, EBV DNA levels appear to correlate with treatment response and may predict disease recurrence, suggesting that they may be an independent indicator of prognosis. The mechanism by which EBV alters nasopharyngeal cells is being elucidated[7] to provide a rational therapeutic target.[7]

Diagnosis

Classification

Nasopharyngeal carcinoma, commonly known as nasopharyngeal cancer, is classified as a malignant [8] Type 2b (III) nonkeratinizing undifferentiated form also known as lymphoepithelioma is most common, and is most strongly associated with Epstein-Barr virus infection of the cancerous cells.[9]

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