**Abstract**

One of the most common types of cancer is head and neck cancer. Head and neck cancers are the sixth most common cancer worldwide and the most common cancer in developing countries. Oral cancer, which is a subset of head and neck cancers, refers to any cancerous growth in the oral cavity. Risk factors for oral cancer include age, malnutrition, genetic factors, family history, X-rays, papilloma virus, alcohol, smoking, tobacco, which three last are the strongest risk factors. The destructive link between tobacco products and human cancers stems from a powerful combination of two factors - nicotine and carcinogens. The highest incidence of tobacco related oral cancer is seen in low and middle income countries. The chance of curing oral cancers increases if they are diagnosed and treated early. At least three-quarters of all oral cancers can be prevented by quitting smoking and drinking alcohol. Screening programs can be valuable in patients from high-risk groups (smokers and alcoholics) or in patients with a previous diagnosis of cancer outside the head and neck.

**Keywords:** head and neck cancer, oral cancer, smoking, tobacco, screening

### **1. Introduction**

In the present century, the rapid growth of non-communicable diseases is considered as a serious health challenge that threatens the socio-economic development of communities and people's health [1]. The most common types of noncommunicable diseases are cardiovascular disease, diabetes, chronic respiratory disease and cancer [2]. Cancers have been known as life-threatening conditions all over the world [3] and recognized as one of the most significant reasons of death around the world and every year, more than 10 million infections and 6 million deaths caused by cancers are reported [4].

One of the most common types of cancer is head and neck cancer [5]. Head and neck cancers are the sixth most common cancer worldwide and the most common cancer in developing countries. While head and neck cancers are one of the most common cancers in South and Southeast Asia, they account for only 1% -4% of all cancers in the Western world [6].

Oral cancer, which is a subset of head and neck cancers, refers to any cancerous growth in the oral cavity. This cancer includes tumors of the lips, tongue, cheeks, gum, floor of the mouth, soft and hard palate, sinuses, tonsils, salivary glands and

throat that can be fatal if left untreated. More than 90% of types of oral cancers originate in the squamous cells that line the inside of the mouth. When the growth of these cells gets out of control, it causes a cancer called squamous cell carcinoma or squamous cell carcinoma. Other types of oral cancers, such as partial malignancies of the salivary glands, sarcomas, odontogenic malignancies, melanoma, and lymphoma, make up less than 10% of oral cancers [7] and approximately 1% of metastatic cancers are lung, breast, prostate and kidney [8]. Squamous cell carcinoma can have various levels of differentiation and often give rise to node metastases. Lymphatic spreading into the neck is directly related to the T stage as well as the depth of invasion and tumor thickness [9].
