Oral Cancer

Oral cancer is a subtype of head and neck cancer, is any cancerous tissue growth located in the oral cavity.^[1] It may arise as a primary lesion originating in any of the oral tissues, by metastasis from a distant site of origin, or by extension from a neighboring anatomic structure, such as the nasal cavity. Alternatively, the Oral cancers may originate in any of the tissues of the mouth, and may be of varied histologic types: teratoma, adenocarcinoma derived from a major or minor salivary gland, lymphoma from tonsillar or other lymphoid tissue, or melanoma from the pigment-producing cells of the oral mucosa. There are several types of oral cancers, but around 90% are squamous cell carcinomas,^[2] originating in the tissues that line the mouth and lips. Oral or mouth cancer most commonly involves the tongue. It may also occur on the floor of the mouth, cheek lining, gingiva (gums), lips, or palate (roof of the mouth). Most oral cancers look very similar under the microscope and are called squamous cell carcinoma.

1.   Signs and Symptoms

 Skin lesion, lump, or ulcer that do not resolve in 14 days located:

• On the tongue, lip, or other mouth areas
• Usually small
• Most often pale colored, be dark or discolored
• Early sign may be a white patch (leukoplakia) or a red patch (erythroplakia) on the soft tissues of the mouth
• Usually painless initially
• May develop a burning sensation or pain when the tumor is advanced
• Behind the wisdom tooth
• Even behind the ear
• Tongue problems
• Swallowing difficulty
• Mouth sores
• Pain and paraesthesia are late symptoms.

 Causes

Oncogenes are activated as a result of mutation of the DNA. The exact cause is often unknown. Regardless of the cause, treatment is the same: surgery, radiation with or without chemotherapy. Risk factors that predispose a person to oral cancer have been identified in epidemiological (epidemiology) studies. India being member of International Cancer Genome Consortium is leading efforts to map oral cancer's complete genome.
It is important to note that around 75 percent of oral cancers are linked to modifiable behaviors such as tobacco use and excessive alcohol consumption. Other factors include poor oral hygiene, irritation caused by ill-fitting dentures and other rough surfaces on the teeth, poor nutrition, and some chronic infections caused by bacteria or viruses. If oral cancer is diagnosed in its earliest stages, treatment is generally very effective.^[3]
In many Asian cultures chewing betel, paan and Areca is known to be a strong risk factor for developing oral cancer. In India where such practices are common, oral cancer represents up to 40% of all cancers, compared to just 4% in the UK.
Some oral cancers begin as leukoplakia a white patch (lesion), red patches, (erythroplakia) or non-healing sores that have existed for more than 14 days. In the US oral cancer accounts for about 8 percent of all malignant growths. Men are affected twice as often as women, particularly men older than 40/60. In Indian subcontinent Oral submucous fibrosis is very common. This condition is characterized by limited opening of mouth and burning sensation on eating of spicy food. This is a progressive lesion in which the opening of the mouth becomes progressively limited, and later on even normal eating becomes difficult. It occurs almost exclusively in India and Indian communities living abroad.

Tobacco

Smoking and other tobacco use are associated with about 75 percent of oral cancer cases,^[4] caused by irritation of the mucous membranes of the mouth from smoke and heat of cigarettes, cigars, and pipes. Tobacco contains over 60 known carcinogens, and the combustion of it, and by products from this process, is the primary mode of involvement. Use of chewing tobacco or snuff causes irritation from direct contact with the mucous membranes.
Tobacco use in any form by itself, and even more so in combination with heavy alcohol consumption, continues to be an important risk factor for oral cancer. However, due to the current trends in the spread of HPV16, as of early 2011 the virus is now considered the primary causative factor in 63% of newly diagnosed patients.

Alcohol

Use of alcohol and other toxic liquids is another high-risk activity associated with oral cancer. There is known to be a very strong synergistic effect on oral cancer risk when a person is both a heavy smoker and drinker. The risk is greatly increased compared to a heavy smoker, or a heavy drinker alone. Recent studies in Australia, Brazil and Germany point to alcohol-containing mouthwashes as also being etiologic agents in the oral cancer risk family. Constant exposure to these alcohol containing rinses, even in the absence of smoking and drinking, lead to significant increases in the development of oral cancer. However, studies conducted in 1985,^[5] 1995,^[6] and 2003^[7] summarize that alcohol-containing mouth rinses are not associated with oral cancer. In a March 2009 brief, the American Dental Association said "the available evidence does not support a connection between oral cancer and alcohol-containing mouthrinse".^[8] A 2008 study suggests that acetaldehyde (a break-down product of alcohol) is implicated in oral cancer.^[9][10] This study specifically focused on abusers of alcohol and made no reference to mouthwash. Any connection between oral cancer and mouthwash is tenuous without further investigation.

Human papillomavirus

Main article: HPV-positive oropharyngeal cancer

Infection with human papillomavirus (HPV), particularly type 16 (there are over 120 types), is a known risk factor and independent causative factor for oral cancer. (Gilsion et al. Johns Hopkins) A fast growing segment of those diagnosed does not present with the historic stereotypical demographics. Historically that has been people over 50, blacks over whites 2 to 1, males over females 3 to 1, and 75% of the time people who have used tobacco products or are heavy users of alcohol. This new and rapidly growing sub population between 20 and 50 years old is predominantly non smoking, white, and males slightly outnumber females. Recent research from Johns Hopkins indicates that HPV is the primary risk factor in this new population of oral cancer victims. HPV16 (along with HPV18) is the same virus responsible for the vast majority of all cervical cancers and is the most common sexually transmitted infection in the US. Oral cancer in this group tends to favor the tonsil and tonsillar pillars, base of the tongue, and the oropharynx. Recent data suggest that individuals that come to the disease from this particular etiology have some slight survival advantage.

Hematopoietic stem cell transplantation

Patients after hematopoietic stem cell transplantation (HSCT) are at a higher risk for oral squamous cell carcinoma. Post-HSCT oral cancer may have more aggressive behavior with poorer prognosis, when compared to oral cancer in non-HSCT patients.^[11] This effect is supposed to be owing to the continuous lifelong immune suppression and chronic oral graft-versus-host disease.^[11]

Diagnosis

On biopsy, the three exophytic masses turned out to be oral carcinomas, while the surrounding hyperkeratotic area showed histologic features of oral lichen planus.

 

An examination of the mouth by the health care provider or dentist shows a visible and/or palpable (can be felt) lesion of the lip, tongue, or other mouth area. As the tumor enlarges, it may become an ulcer and bleed. Speech/talking difficulties, chewing problems, or swallowing difficulties may develop. A feeding tube is often necessary to maintain adequate nutrition. This can sometimes become permanent as eating difficulties can include the inability to swallow even a sip of water.
There are a variety of screening devices that may assist dentists in detecting oral cancer, including the Velscope, Vizilite Plus and the identafi 3000. While a dentist, physician or other health professional may suspect a particular lesion is malignant, there is no way to tell by looking alone - since benign and malignant lesions may look identical to the eye. A non-invasive brush biopsy (BrushTest) can be performed to rule out the presence of dysplasia (pre-cancer) and cancer on areas of the mouth that exhibit an unexplained color variation or lesion. The only definitive method for determining if cancerous or precancerous cells are present is through biopsy and microscopic evaluation of the cells in the removed sample. A tissue biopsy, whether of the tongue or other oral tissues and microscopic examination of the lesion confirm the diagnosis of oral cancer or precancer.

Management

Surgical excision (removal) of the tumor is usually recommended if the tumor is small enough, and if surgery is likely to result in a functionally satisfactory result. Radiation therapy with or without chemotherapy is often used in conjunction with surgery, or as the definitive radical treatment, especially if the tumour is inoperable. Surgeries for oral cancers include

• Maxillectomy (can be done with or without Orbital exenteration)
• Mandibulectomy (removal of the mandible or lower jaw or part of it)
• Glossectomy (tongue removal, can be total, hemi or partial)
• Radical neck dissection
• Moh's procedure or CCPDMA
• Combinational e.g. glossectomy and laryngectomy done together.
• Feeding tube to sustain nutrition.

Owing to the vital nature of the structures in the head and neck area, surgery for larger cancers is technically demanding. Reconstructive surgery may be required to give an acceptable cosmetic and functional result. Bone grafts and surgical flaps such as the radial forearm flap are used to help rebuild the structures removed during excision of the cancer. An oral prosthesis may also be required. Most oral cancer patients depend on a feeding tube for their hydration and nutrition. Some will also get a port for the chemo to be delivered. Many oral cancer patients are disfigured and suffer from many long term after effects. The after effects often include fatigue, speech problems, trouble maintaining weight, thyroid issues, swallowing difficulties, inability to swallow, memory loss, weakness, dizziness, high frequency hearing loss and sinus damage.
Survival rates for oral cancer depend on the precise site, and the stage of the cancer at diagnosis. Overall, survival is around 50% at five years when all stages of initial diagnosis are considered. Survival rates for stage 1 cancers are 90%, hence the emphasis on early detection to increase survival outcome for patients.
Following treatment, rehabilitation may be necessary to improve movement, chewing, swallowing, and speech. Speech and language pathologists may be involved at this stage.
Chemotherapy is useful in oral cancers when used in combination with other treatment modalities such as radiation therapy. It is not used alone as a monotherapy. When cure is unlikely it can also be used to extend life and can be considered palliative but not curative care. Biological agents, such as Cetuximab have recently been shown to be effective in the treatment of squamous cell head and neck cancers, and are likely to have an increasing role in the future management of this condition when used in conjunction with other treatments.
Treatment of oral cancer will usually be by a multidisciplinary team, with treatment professionals from the realms of radiation, surgery, chemotherapy, nutrition, dental professionals, and even psychology all possibly involved with diagnosis, treatment, rehabilitation, and patient care.

Sources :  http://en.wikipedia.org/wiki/Oral_cancer