Head and neck region include various anatomical structure present between the base of the skull and the clavicles. The anatomical structures mainly include the oral cavity, oropharynx, larynx, hypopharynx, nasopharynx, nasal cavity, and salivary glands. HNC is a group of different neoplasms with variable characteristics.
Most are squamous cell carcinoma (SCC) or its variants that generally arise from the cells in the surface epithelium that line the anatomical structures in the head and neck region. SCCs usually develop from surface lesions such as carcinoma in situ (CIS) that develop from cells with early dysplastic changes. Following are the risk factors for head and neck cancers.
Tobacco/cigarette Smoking and Alcohol Consumption
Use of tobacco is one of the major risk factors for HNCs with the higher risk involved for the greater amount used. Smokers are at 3 times higher risk of developing HNCs compared to non-smokers. Alcohol consumption also increases the risk of HNCs, especially heavy alcohol intake. Using both tobacco and alcohol together multiplies the risk of getting HNCs.
Human Papilloma Virus (HPV) Infection
HPV is a group of about 150 DNA viruses with high-risk subtypes including HPV-16 and HPV-18 that are found in about 70% of all the cases of HNCs. Researchers believe that HPV consists of two proteins known as E6 and E7 which inactivate some tumor suppressor genes and lead to the development of HNCs. HPV infection is found to be associated with many cases of HNCs, especially in the oropharynx.
Genetic cancer predsposition syndromes
Some inherited cancer predisposition syndromes (caused by a mutation in certain genes which are generally transferred from one generation to other) have been reported to be associated with a high incidence rate of HNCs. For example, Fanconi anemia and Dyskeratosis congenita may be associated with oral cavity and laryngeal cancers.
Risk of developing certain HNCs increases in an individual with a history of HNC in close relatives, or in individuals with a personal history of any other type of HNC.
Higher risk of HNCs has also been reported in individuals with chronic exposure to certain chemicals like paint, dye, heavy metals, petroleum products, formaldehyde, asbestos, nickel, chromium, generally experienced by the workers of plastic, textile, dyestuffs, paint, leather, dry-cleaning, and metal industries. Additionally, exposure to wood dust, flour, mustard gas, and radium has been reported to increase the risk of developing HNCs.
Weakened immune system
Individuals with a weak immune system that may be due to HIV infection, autoimmune disease, or immunosuppresants in patients who have undergone an organ transplant are considered at higher risk of developing certain types of HNCs, for example, cancer of the oral cavity.
History of exposure to radiation
Radiation to the head and neck region or for the treatment of hereditary retinoblastoma has been implicated for the development of cancer of the salivary glands and paranasal sinuses.
Age and Gender
Older age individuals, especially males are generally at increased risk of developing HNCs. The gender disparity is thought because of higher tobacco and alcohol consumption by males.
Gastroesophageal reflux disease (GERD)
GERD has been reported to increase the risk of laryngeal and hypopharyngeal cancers.
Poor nutrition has been reported as one of the risk factors for the development of HNCs. The exact mechanism is unknown.
Diet very high in salt-cured fish and meat (common in parts of Asia, northern Africa, and the Arctic region) and Epstein-Barr virus infection (mostly associated with nasopharyngeal cancers) are some other risk factors for the development of HNCs.