This form of cancer is often seen in those who chew tobacco or use snuff orally, so much so that it is sometimes referred to as "Snuff dipper's cancer." Chewing betel nuts is an additional risk factor commonly seen in Taiwan.

Squamous cell carcinoma of eye tissues is one of the most frequent neoplasms of cattle.

Between 250,000 and 1 million American women are diagnosed with CIN annually. Women can develop CIN at any age, however women generally develop it between the ages of 25 to 35.

The incidence of squamous cell carcinoma continues to rise around the world. A recent study estimated that there are between 180,000 and 400,000 cases of SCC in the United States in 2013. Risk factors for squamous cell carcinoma varies with age, gender, race, geography, and genetics. The incidence of SCC increases with age and the peak incidence is usually around 60 years old. Males are affected with SCC at a ratio of 2:1 in comparison to females. Caucasians are more likely to be affected, especially those with fair Celtic skin and chronically exposed to UV radiation. Squamous cell carcinoma of the skin is the most common among all sites of the body. Solid organ transplant recipients (heart, lung, liver, pancreas, among others) are also at a heightened risk of developing aggressive, high-risk SCC. There are also a few rare congenital diseases predisposed to cutaneous malignancy. In certain geographic locations, exposure to arsenic in well water or from industrial sources may significantly increase the risk of SCC.

When associated with the lung, it is typically a centrally located large cell cancer (non-small cell lung cancer or NSCLC). It often has a paraneoplastic syndrome causing ectopic production of parathyroid hormone-related protein (PTHrP), resulting in hypercalcemia, however paraneoplastic syndrome is more commonly associated with small cell lung cancer.

It is primarily due to smoking.

The long-term outcome of squamous cell carcinomas is dependent upon several factors: the sub-type of the carcinoma, available treatments, location(s) and severity, and various patient health-related variables (accompanying diseases, age, etc.). Generally, the long-term outcome is positive, as less than 4% of Squamous cell carcinoma cases are at risk of metastasis. Some particular forms of squamous cell carcinomas have a higher mortality rate. One study found squamous cell carcinoma of the penis had a much greater rate of mortality than some other forms of squamous cell carcinoma, that is, about 23%, although this relatively high mortality rate may be associated with possibly latent diagnosis of the disease due to patients avoiding genital exams until the symptoms are debilitating, or refusal to submit to a possibly scarring operation upon the genitalia. Squamous cell carcinoma occurring in the organ transplant population is also associated with a higher risk of mortality.

Human papillomavirus infection (HPV) has been associated with SCC of the oropharynx, lung, fingers and anogenital region.

Lymphoma is the most common type of blood-related cancer in horses and while it can affect horses of all ages, it typically occurs in horses aged 4–11 years.

Verrucous carcinoma (VC) is an uncommon variant of squamous cell carcinoma. This form of cancer is often seen in those who chew tobacco or use snuff orally, so much so that it is sometimes referred to as "Snuff dipper's cancer."

Most patients with verrucous carcinoma have a good prognosis. Local recurrence is not uncommon, but metastasis to distant parts of the body is rare. Patients with oral verrucous carcinoma may be at greater risk of a second oral squamous cell carcinoma, for which the prognosis is worse.

Verrucous carcinoma may occur in various head and neck locations, as well as in the genitalia. The oral cavity is the most common site of this tumor. The ages range from 50 to 80 years with a male predominance and a median age of 67 years. VC may grow large in size, resulting in the destruction of adjacent tissue, such as bone and cartilage.

The diagnosis of VC is established by close communication between surgeons and pathologists.

Surgeons must provide adequate specimens including the full thickness of the tumors and adjacent uninvolved mucosa for correct diagnoses.

Surgery is considered as the treatment of choice, but the extent of surgical margin and the adjuvant radiotherapy are still controversial.

The major risk factors are cigarette smoking and alcohol consumption, while betel nut is an additional factor in Taiwan. Different gene mutation sites in head and neck cancer between western countries and Taiwan have been reported. The presentation of VC originated from exposure to different carcinogens may not be the same.

Although the exact cause of vulvar cancer isn't known, certain factors appear to increase your risk of the disease.

- Increasing age

- Exposure to human papillomavirus

- Smoking

- Being infected with the human immunodeficiency virus (HIV)

- Having a history of precancerous conditions of the vulva

- Having a skin condition involving the vulva

Vaccinating girls with HPV vaccine before their initial sexual contact has been claimed to reduce incidence of VIN.

It used to be thought that cases of CIN progressed through these stages toward cancer in a linear fashion.

However most CIN spontaneously regress. Left untreated, about 70% of CIN-1 will regress within one year, and 90% will regress within two years. About 50% of CIN 2 will regress within 2 years without treatment.

Progression to cervical carcinoma in situ (CIS) occurs in approximately 11% of CIN1 and 22% of CIN2. Progression to invasive cancer occurs in approximately 1% of CIN1, 5% in CIN2 and at least 12% in CIN3.

Progression to cancer typically takes 15 (3 to 40) years. Also, evidence suggests that cancer can occur without first detectably progressing through these stages and that a high grade intraepithelial neoplasia can occur without first existing as a lower grade.

It is thought that the higher risk HPV infections, have the ability to inactivate tumor suppressor genes such as the p53 gene and the RB gene, thus allowing the infected cells to grow unchecked and accumulate successive mutations, eventually leading to cancer.

Treatment does not affect the chances of getting pregnant but does increase the risk of second trimester miscarriages.

Some conditions such as lichen sclerosus, squamous dysplasia or chronic vulvar itching may precede cancer. In younger women affected with vulvar cancer, risk factors include low socioeconomic status, multiple sexual partners, cigarette use and cervical cancer. Patients that are infected with HIV tend to be more susceptible to vulvar cancer as well. Human papillomavirus (HPV) infection is associated with vulvar cancer.

The exact cause of VIN is unknown. Studies are being done to determine the cause of VIN. The following factors have been associated with VIN:

- HPV (Human Papilloma Virus)

- HSV-2 (Herpes simplex Virus - Type 2)

- Smoking

- Immunosuppression

- Chronic vulvar irritation

- Conditions such as Lichen Sclerosus

Use of the kangri pot has been correlated with the risk of Kangri cancer. The pot holds hot wood and charcoal, and as a unit, the pot is put in direct contact with the skin of the abdomen and the thigh areas as a way to keep warm during winters in north India. Elements that are believed to contribute to the development of Kangri cancer are heat, burning wood particles, smoke, soot, and tar of burnt chinar leaves that could also be used as a fuel source for burning in the production of heat.

In one study, researchers noted kangri pot usage patterns and found that Kangri cancer “patients gave the history of using the Kangri especially for 3-4 winter months [...] every year for 5-6 hours daily.”

Beyond the behavioral risk factor of prolonged usage of Kangri pots, researchers have begun to look at genetic mutations that may make some people more predisposed to develop Kangri cancer.

- In one study, compared to a control group, people with Kangri cancer were found to be approximately twice as likely to have a mutation in the TP53 gene (codon 72 polymorphism). Patients with higher grade tumors exhibited more proline amino acid mutations at this site.

- Another study confirmed this association of Kangri Cancer and TP53 mutations, specifically substitutions and insertions, in 40% of the Kangri cancer patients who were studied. The researchers observed a significant correlation with mutation status and age as well as with the presence of lymph nodes in patients. TP53 may, in the future, serve as “potential molecular marker and prognostic tool” for Kangri cancer. Furthermore, PTEN mutations were found in two of thirty patients studied; though due to the small sample size, no useful conclusions could be postulated.

- Two polymorphisms of the HSP70 gene were discovered to be correlated with “poor prognosis” of Kangri cancer; the “Hsp70-2 A/G or G/G and Hsp70homC/C genotypes” could potentially be utilized to measure risk of Kangri cancer development as well as to predict prognosis.

Normally found in children or young adults, a common cause of conjunctival squamous cell papilloma is during childbirth, when the mother passes the virus to her child.

Immunoperoxidase stains have identified antigens of the human papillomavirus (HPV) types 6 and 11 in approximately 50% of cases of squamous cell papilloma.

Ultraviolet radiation from sun exposure is the primary environmental cause of skin cancer. Other risk factors that play a role include:

- Smoking tobacco

- HPV infections increase the risk of squamous-cell skin cancer.

- Some genetic syndromes including congenital melanocytic nevi syndrome which is characterized by the presence of nevi (birthmarks or moles) of varying size which are either present at birth, or appear within 6 months of birth. Nevi larger than 20 mm (3/4") in size are at higher risk for becoming cancerous.

- Chronic non-healing wounds. These are called Marjolin's ulcers based on their appearance, and can develop into squamous-cell skin cancer.

- Ionizing radiation such as X-rays, environmental carcinogens, artificial UV radiation (e.g. tanning beds), aging, and light skin color. It is believed that tanning beds are the cause of hundreds of thousands of basal and squamous-cell skin cancer. The World Health Organization now places people who use artificial tanning beds in its highest risk category for skin cancer. Alcohol consumption, specifically excessive drinking increase the risk of sunburns.

- The use of many immunosuppressive medications increases the risk of skin cancer. Cyclosporin A, a calcineurin inhibitor for example increases the risk approximately 200 times, and azathioprine about 60 times.

Around 75% of cases are caused by alcohol and tobacco use.

Tobacco smoke is one of the main risk factors for head and neck cancer and one of the most carcinogenic compounds in tobacco smoke is acrylonitrile. (See Tobacco smoking). Acrylonitrile appears to indirectly cause DNA damage by increasing oxidative stress, leading to increased levels of 8-oxo-2'-deoxyguanosine (8-oxo-dG) and formamidopyrimidine in DNA (see image). Both 8-oxo-dG and formamidopyrimidine are mutagenic. DNA glycosylase NEIL1 prevents mutagenesis by 8-oxo-dG and removes formamidopyrimidines from DNA.

However, cigarette smokers have a lifetime increased risk for head and neck cancers that is 5- to 25-fold increased over the general population.

The ex-smoker's risk for squamous cell cancer of the head and neck begins to approach the risk in the general population twenty years after smoking cessation. The high prevalence of tobacco and alcohol use worldwide and the high association of these cancers with these substances makes them ideal targets for enhanced cancer prevention.

Smokeless tobacco is cause of oral and pharyngeal cancers (oropharyngeal cancer). Cigar smoking is an important risk factor for oral cancers as well.

Other environmental carcinogens suspected of being potential causes of head and neck cancer include occupational exposures such as nickel refining, exposure to textile fibers, and woodworking. Use of marijuana, especially while younger, is linked to an increase in squamous-cell carcinoma cases while other studies suggest use is not shown to be associated with oral squamous cell carcinoma, or associated with decreased squamous cell carcinoma.

Conjunctival Squamous Cell Carcinoma (Conjunctival SCC) and corneal intraepithelial neoplasia comprise what are called Ocular Surface Squamous Cell Neoplasias. SCC is the most common malignancy of the conjunctiva in the US, with a yearly incidence of 1-2.8 per 100,000. Risk factors for the disease are exposure to sun (specifically occupational), exposure to UVB, and light-colored skin. Other risk factors include radiation, smoking, HPV, arsenic, and exposure to polycyclic hydrocarbons.

Conjunctival SCC is often asymptomatic at first, but it can present with the presence of a growth, red eye, pain, itching, burning, tearing, sensitivity to light, double vision, and decreased vision.

Spread of conjunctival SCC can occur in 1-21% of cases, with the first site of spread being the regional lymph nodes. Mortality for conjunctival SCC ranges from 0-8%.

Diagnosis is often made by biopsy, as well as CT (in the case of invasive SCC).

Treatment of Conjunctival SCC is usually surgical excision followed by cryotherapy. After this procedure, Conjunctival SCC can recur 8-40% of the time. Radiation treatment, topical Mitomycin C, and removal of the contents of the orbit, or exenteration, are other methods of treatment. Close follow-up is recommended, because the average time to recurrence is 8–22 months.

Keratoacanthoma usually occurs in older individuals. As with squamous cell cancer, it seems likely that ultraviolet light from the sun causes the development of KA. As with squamous cell cancer, sporadic cases have been found co-infected with the human papilloma virus (HPV).

Many new treatments for Melanoma are also known to increase the rate of Keratoacanthoma, such as the B-Raf inhibitor drugs Vemurafenib and Dabrafenib.

Excessive consumption of processed meats and red meat were associated with increased rates of cancer of the head and neck in one study, while consumption of raw and cooked vegetables seemed to be protective.

Vitamin E was not found to prevent the development of leukoplakia, the white plaques that are the precursor for carcinomas of the mucosal surfaces, in adult smokers.

Another study examined a combination of Vitamin E and beta carotene in smokers with early-stage cancer of the oropharynx, and found a worse prognosis in the vitamin users.

Erythroplakia has an unknown cause but researchers presume it to be similar to the causes of squamous cell carcinoma. Carcinoma is found in almost 40% of erythroplakia. It is mostly found in elderly men around the ages of 65 - 74. It is commonly associated with smoking.

Alcohol and tobacco use have been described as risk factors.

Squamous cell papilloma of the mouth or throat is generally diagnosed in people between the ages of 30 and 50, and is normally found on the inside of the cheek, on the tongue, or inside of lips. Oral papillomas are usually painless, and not treated unless they interfere with eating or are causing pain. They do not generally mutate to cancerous growths, nor do they normally grow or spread. Oral papillomas are most usually a result of the infection with types HPV-6 and HPV-11.