In its early stages, it can go unnoticed. It can be painless with slight physical changes. But the precursor tissue changes, can be noticed by the doctors.

Early stage symptoms can include persistent red or white patches, a non-healing ulcer, progressive swelling or enlargement, unusual surface changes, sudden tooth mobility without apparent cause, unusual oral bleeding or epitaxis and prolonged hoarseness.

Late stage symptoms can include an indurated area, paresthesia or dysesthesia of the tongue or lips, airway obstruction, chronic serous otitis media, otalgia, trismus, dysphagia, cervical lymphadenopathy, persistent pain or referred pain and altered vision.

The possible signs of oropharyngeal cancer are:

- A sore throat that persists

- Pain or difficulty with swallowing

- Unexplained weight loss

- Voice changes

- Ear pain

- A lump in the back of the throat or mouth

- A lump in the neck

- A dull pain behind the sternum

- Cough

Throat cancer usually begins with symptoms that seem harmless enough, like an enlarged lymph node on the outside of the neck, a sore throat or a hoarse sounding voice. However, in the case of throat cancer, these conditions may persist and become chronic. There may be a lump or a sore in the throat or neck that does not heal or go away. There may be difficult or painful swallowing. Speaking may become difficult. There may be a persistent earache. Other possible but less common symptoms include some numbness or paralysis of the face muscles.

Presenting symptoms include :

- Mass in the neck

- Neck pain

- Bleeding from the mouth

- Sinus congestion, especially with nasopharyngeal carcinoma

- Bad breath

- Sore tongue

- Painless ulcer or sores in the mouth that do not heal

- White, red or dark patches in the mouth that will not go away

- Earache

- Unusual bleeding or numbness in the mouth

- Lump in the lip, mouth or gums

- Enlarged lymph glands in the neck

- Slurring of speech (if the cancer is affecting the tongue)

- Hoarse voice which persists for more than six weeks

- Sore throat which persists for more than six weeks

- Difficulty swallowing food

- Change in diet or weight loss

Oral cancer, also known as mouth cancer, is a type of head and neck cancer and is any cancerous tissue growth located in the oral cavity.

It may arise as a primary lesion originating in any of the tissues in the mouth, 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, 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, but less commonly other types of oral cancer occur, such as Kaposi's sarcoma.

In 2013 oral cancer resulted in 135,000 deaths up from 84,000 deaths in 1990. Five-year survival rates in the United States are 63%.

Squamous cell cancers are common in the mouth, including the inner lip, tongue, floor of mouth, gingivae, and hard palate. Cancers of the mouth are strongly associated with tobacco use, especially use of chewing tobacco or "dip", as well as heavy alcohol use. Cancers of this region, particularly the tongue, are more frequently treated with surgery than are other head and neck cancers.

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

- Mohs procedure

- Combinational e.g., glossectomy and laryngectomy done together.

The defect is typically covered/improved by using another part of the body and/or skin grafts and/or wearing a prosthesis.

Oropharyngeal cancer is a disease in which cancer form in the tissues of the throat (oropharynx). The oropharynx is the middle part of the throat that includes the base of the tongue, the tonsils, the soft palate, and the walls of the pharynx. Oropharyngeal cancers can be divided into two types, HPV-positive, which are related to human papillomavirus infection, and HPV-negative cancers, which are usually linked to alcohol or tobacco use.

Esophageal cancer may be due to either squamous cell carcinoma (ESCC) or adenocarcinoma (EAC). SCCs tend to occur closer to the mouth, while adenocarcinomas occur closer to the stomach. Dysphagia (difficulty swallowing, solids worse than liquids) and painful swallowing are common initial symptoms. If the disease is localized, surgical removal of the affected esophagus may offer the possibility of a cure. If the disease has spread, chemotherapy and radiotherapy are commonly used.

Ninety percent of cases of head and neck cancer (cancer of the mouth, nasal cavity, nasopharynx, throat and associated structures) are due to squamous cell carcinoma.

Symptoms of Hypopharyngeal Cancer include:

- Swollen lymph nodes in the neck (first sign of a problem in half of all patients)

- Sore throat in one location that persists after treatment

- Pain that radiates from the throat to the ears

- Difficult or painful swallowing (often leads to malnutrition and weight loss because of a refusal to eat)

- Voice changes (late stage cancer)

Head and neck cancers are malignant neoplasms that arise in the head and region which comprises nasal cavity, paranasal sinuses, oral cavity, salivary glands, pharynx, and larynx. Majority of head and neck cancers histologically belong to squamous cell type and hence they are categorized as Head and Neck Squamous Cell Carcinoma (abbreviated as HNSCC)[Forastiere AA, 2003]. HNSCC are the 6th most common cancers worldwide and 3rd most common cancers in developing world. They account for ~ 5% of all malignancies worldwide (Ferlay J, 2010) and 3% of all malignancies in the United States (Siegel R, 2014).

Risk factors include tobacco consumption (chewing or smoking), alcohol consumption, Epstein-Barr virus (EBV) infection, human papilloma virus (HPV; esp. HPV 16, 18) infection, betel nut chewing, wood dust exposures, consumption of certain salted fish and others (NCI Factsheet, 2013). EBV infection has been specifically associated with nasopharyngeal cancer. Reverse smoking was considered as a risk factor for oral cancer. Interestingly, "Cis-retinoic acid" (i.e. supplements of retinoic acid) intake may increase the risk of HNSCC in active smokers. Low consumption of fruits and vegetables was associated with higher incidence of HNSCC.

HNSCC classification: Based on the HPV infection status, head and neck cancers are classified into HPV-positive and HPV-negative categories. So far, this is the only available molecular classification. Majority (>50%) of oral cancers are HPV-positive in the U.S. HPV-positive oral cancers are widely prevalent in younger patients and are associated with multiple sexual partners and oral sexual practices. HPV-positive cancers have better prognosis, especially for nonsmokers as compared to HPV-negative cancers.

Staging and grading of HNSCC: HNSCC are classified according to the tumor-node-metastasis (TNM) system of American Joint Committee on cancer. TNM staging system for HNSCC are discussed else where.

Symptoms include lump or sore, sore throat, hoarse of voice, difficulty in swallowing etc (NCI Factsheet, 2013).

Treatment for HNSCC is predominantly based on the stage of the disease. Factors such as patient fitness, baseline swallow, airway functional status, and others are considered before determining the treatment plan. Standard of care for HNSCC includes one or combination of the following: surgery, radiation, chemotherapeutic agents such as Cisplatin, 5-Flurouracil (5-FU) etc. Molecularly targeted therapies were developed since the discovery of role of epidermal growth factor receptor (EGFR) signaling in HNSCC development, progression and prognosis. These targeted therapies include monoclonal antibodies (such as cetuximab, panitumumab etc.) and tyrosine kinase inhibitors (such as erlotinib, gefitinib, etc.). Among these EGFR-targeting agents, only cetuximab has been approved by FDA in 2006 for HNSCC treatment.

Ninety percent (MacMillan, 2015) of cases of head and neck cancer (cancer of the mouth, nasal cavity, nasopharynx, throat and associated structures) are due to squamous cell carcinoma. Symptoms may include a poorly healing mouth ulcer, a hoarse voice or other persistent problems in the area. Treatment is usually with surgery (which may be extensive) and radiotherapy. Risk factors include smoking, alcohol consumption and hematopoietic stem cell transplantation (Elad S, Zadik Y, Zeevi I, et al., 2010, pp. 1243–1244). In addition, recent studies show that about 25% of mouth and 35% of throat cancers are associated with HPV. The 5 year disease free survival rate for HPV positive cancer is significantly higher when appropriately treated with surgery, radiation and chemotherapy as compared to non-HPV positive cancer, substantiated by multiple studies including research conducted by Maura Gillison, "et al." of Johns Hopkins Sidney Kimmel Cancer Center.

Symptoms that may be caused by urethral cancer include:

Bleeding from the urethra or blood in the urine,

Weak or interrupted flow of urine,

Urination occurs often, painful urination, inability to pass urine,

A lump or thickness in the perineum or penis,

Discharge from the urethra,

Enlarged lymph nodes or pain in the groin or vaginal area.

STK typically occurs in the buccal sulcus (inside the cheek) or the labial sulcus (between the lips and the teeth) and corresponds to the site where the tobacco is held in the mouth. It is painless.

The appearance of the lesion is variable depending upon the type of tobacco used, and the frequency and duration of use. It takes about 1-5 years of smokeless tobacco use for the lesion to appear. Early lesions may appear as thin, translucent and granular or wrinkled mucosa. The later lesion may appear thicker, more opaquely white and hyperkeratotic with fissures and folds. Oral snuff causes more pronounced changes in the oral mucosa than tobacco chewing. Snuff dipping is associated more with verrucous keratosis.

As well as the white changes of the oral mucosa, there may be gingival recession (receding gums) and staining of tooth roots in the area where the tobacco is held.

Hypopharyngeal cancer is a disease in which malignant cells grow in the hypopharynx (the area where the larynx and esophagus meet).

It first forms in the outer layer (epithelium) of the hypopharynx (last part of the pharynx), which is split into three areas. Progression of the disease is defined by the spread of cancer into one or more areas and into deeper tissues.

This type of cancer is rare. Only about 2,500 cases are seen in the US each year. Because of this, Hypopharyngeal Cancer is difficult to catch in its earliest stages and has one of the highest mortality rates of any head and neck cancer.

Cancer patients undergoing chemotherapy usually become symptomatic four to five days after beginning treatment, reaching a peak at around day 10, and then slowly improving over the course of a few weeks. Mucositis associated with radiotherapy usually appears at the end of the second week of treatment and may last for six to eight weeks.

As a result of cell death in reaction to chemo- or radio-therapy, the mucosal lining of the mouth becomes thin, may slough off and then become red, inflamed and ulcerated. The ulcers may become covered by a yellowish white fibrin clot called a pseudomembrane. Peripheral erythema is usually present. Ulcers may range from 0.5 cm to greater than 4 cm. Oral mucositis can be severely painful. The degree of pain is usually related to the extent of the tissue damage. Pain is often described as a burning sensation accompanied by reddening. Due to pain, the patient may experience trouble speaking, eating, or even opening the mouth.

Dysgeusia, or an alteration in taste perception, is common, especially for those who are receiving concomitant radiation therapy to the neck and mouth area. "Taste blindness", or an altered sense of taste, is a temporary condition that occurs because of effects on taste buds that are mostly located in the tongue. Sometimes, only partial recovery of taste occurs. Common complaints are of food tasting too sweet or too bitter or of a continuous metallic taste.

Although often the terms "erythroplasia" and "erythroplakia" are used synonymously, some sources distinguish them, stating that the latter is maccular (flat) while the former is papular (bumpy).

Erythroplakia of the genital mucosae is often referred to as erythroplasia of Queyrat.

The most common areas in the mouth where erythroplakia is found are the floor of the mouth, buccal vestibule, the tongue, and the soft palate. It appears as a red macule or plaque with well-demarcated borders. The texture is characterized as soft and velvety. An adjacent area of leukoplakia may be found along with the erythroplakia.

Erythroplasia may also occur on the laryngeal mucosa, or the anal mucosa.

The main medical risk factors are having bladder cancer or having conditions that cause chronic inflammation in the urethra. People over the age of 60 and white women have the highest risks.

Mucositis is the painful inflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer. Mucositis can occur anywhere along the gastrointestinal (GI) tract, but oral mucositis refers to the particular inflammation and ulceration that occurs in the mouth. Oral mucositis is a common and often debilitating complication of cancer treatment.

Oral and gastrointestinal (GI) mucositis affects almost all patients undergoing high-dose chemotherapy and hematopoietic stem cell transplantation (HSCT), 80% of patients with malignancies of the head and neck receiving radiotherapy, and a wide range of patients receiving chemotherapy. Alimentary tract mucositis increases mortality and morbidity and contributes to rising health care costs.

For most cancer treatment, about 5–15% of patients get mucositis. However, with 5-fluorouracil (5-FU), up to 40% get mucositis, and 10–15% get grade 3–4 oral mucositis. Irinotecan is associated with severe GI mucositis in over 20% of patients. Seventy-five to eighty percent of bone marrow transplantation recipients experience mucositis, of which oral mucositis is the most common and most debilitating, especially when melphalan is used. In grade 3 oral mucositis, the patient is unable to eat solid food, and in grade 4, the patient is unable to consume liquids as well.

Radiotherapy to the head and neck or to the pelvis or abdomen is associated with Grade 3 and Grade 4 oral or GI mucositis, respectively, often exceeding 50% of patients. Among patients undergoing head and neck radiotherapy, pain and decreased oral function may persist long after the conclusion of therapy. Fractionated radiation dosage increases the risk of mucositis to > 70% of patients in most trials. Oral mucositis is particularly profound and prolonged among HSCT recipients who receive total-body irradiation.

Smokeless tobacco keratosis (abbreviated to STK, also termed snuff dippers' keratosis, smokeless tobacco-associated keratosis, snuff pouch, snuff dipper's lesion, tobacco pouch keratosis, or spit tobacco keratosis) is a condition which develops on the oral mucosa (the lining of the mouth) in response to smokeless tobacco use. Generally it appears as a white patch, located at the point where the tobacco is held in the mouth. The condition usually disappears once the tobacco habit is stopped. It is associated with slightly increased risk of mouth cancer.

In the context of lesions of the mucous membrane lining of the bladder, leukoplakia is a historic term used to describe a visualized white patch which histologically represents keratinization in an area of squamous metaplasia. The symptoms may include frequency, suprapubic pain (pain felt above the pubis), hematuria (blood in the urine), dysuria (difficult urination or pain during urination), urgency, and urge incontinence. The white lesion may be seen during cystoscopy, where it appears as a whitish-gray or yellow lesion, on a background of inflamed urothelium and there may be floating debris in the bladder. Leukoplakia of the bladder may undergo cancerous changes, so biopsy and long term follow up are usually indicated.

Leukoplakia could be classified as mucosal disease, and also as a premalignant condition. Although the white color in leukoplakia is a result of hyperkeratosis (or acanthosis), similarly appearing white lesions that are caused by reactive keratosis (smoker's keratosis or frictional keratoses e.g. morsicatio buccarum) are not considered to be leukoplakias. Leukoplakia could also be considered according to the affected site, e.g. oral leukoplakia, leukoplakia of the urinary tract, including bladder leukoplakia or leukoplakia of the penis, vulvae, cervix or vagina. Leukoplakia may also occur in the larynx, possibly in association with gastro-esophageal reflux disease. Oropharyngeal leukoplakia is linked to the development of esophageal squamous cell carcinoma, and sometimes this is associated with tylosis, which is thickening of the skin on the palms and soles of the feet (see: Leukoplakia with tylosis and esophageal carcinoma). Dyskeratosis congenita may be associated with leukoplakia of the oral mucosa and of the anal mucosa.

There are many other conditions that are similar in appearance and must be ruled out before a diagnosis of erythroplakia is made (see table). Sometimes, a diagnosis is delayed for up to two weeks in order to see if the lesion spontaneously regresses on its own or if another cause can be found. Erythroplakia frequently is associated with dysplasia, and is thus a precancerous lesion.

The palate may appear gray or white and contain many papules or nodules that are slightly elevated with red dots in their center. These red dots represent the ducts of minor salivary glands which have become inflamed by heat. The condition is painless. If a denture is normally worn while smoking, then the mucosa underneath the denture appears unaffected by the condition. In severe cases, the mucosa may show fissuring and develop a "dried lake bed" appearance. Other changes associated with tobacco use may be evident such as brown or black extrinsic staining of teeth from tar and other components of tobacco smoke.

Stomatitis nicotina (also known as nicotine stomatitis, nicotinic stomatitis, nicotine palatinus, stomatitis palatini, leukokeratosis nicotina palate, palatal leukokeratosis, smoker's keratosis, smoker's palate, and smoker's patches), is a diffuse white patch on the hard palate, usually caused by tobacco smoking, usually pipe or cigar smoking. It is painless, and it is caused by a response of the palatal oral mucosa to chronic heat. A more pronounced appearance can occur with reverse smoking, sometimes distinguished from stomatitis nicotina by the term reverse smoker's keratosis. While stomatitis nicotina that is caused by heat is not a premaligant condition (i.e. it does not carry an increased risk of transformation to oral cancer), the condition that is caused by reverse smoking is premalignant.

There is a diffuse, gray-white, milky opalescent appearance of the mucosa which usually occurs bilaterally on the buccal mucosa. Less often, the labial mucosa, the palate or the floor of mouth may be affected. The surface of the area is folded, creating a wrinkled, white streaked lesion. Apart from the appearance, the lesion is entirely asymptomatic.

Salivary gland tumours usually present as a lump or swelling in the affected gland which may or may not have been present for a long time. The lump may be accompanied by symptoms of duct blockage (e.g. xerostomia). Usually, in their early stages it is not possible to distinguish a benign tumour from a malignant one. One of the key differentiating symptoms of a malignant growth is nerve involvement. For example signs of facial nerve damage (e.g facial palsy) are associated with malignant parotid tumours. Facial pain, and paraesthesia are also very often associated with a malignant tumours. Other red flag symptoms which may suggest malignancy and warrant further investigation are fixation of the lump to the overlying skin, ulceration and induration of the mucosa.