Squamous Cell Carcinoma Causes and Risk Factors

Squamous cell carcinoma (SCC) is a common cancer that develops in the thin, flat cells that make up the outermost layer of skin (epidermis). Symptoms can include firm red nodules, scaly sores and wart-like growths, often appearing on sun-exposed areas, such as the face, neck and hands. SCC can also develop in other parts of the body where squamous cells are present, such as the mouth, throat and lungs.

The second most common type of non-melanoma skin cancer in the United States, squamous cell carcinoma is especially prevalent among older adults, fair-skinned individuals and those with frequent sun exposure or a weakened immune system. Treatment options can include removal of the skin lesion through cryotherapy, Mohs micrographic surgery, surgical excision, radiation therapy or a topical cream or gel. When detected early, SCC can be treated effectively and often cured.

What causes squamous cell carcinoma?

SCC is primarily caused by DNA damage in the squamous cells, often resulting from prolonged exposure to ultraviolet (UV) radiation. Normally, healthy skin cells regenerate every few days. As old cells die, they are pushed to the surface of the skin by the new cells forming directly underneath them. The old cells naturally detach and shed from the skin with friction from clothing or bathing. DNA damage can disrupt the orderly cell renewal process, allowing abnormal cells to build up and form cancerous skin lesions. SCC spreads slowly, but if left untreated, it can invade nearby lymph nodes, bones and other tissues.

What are the risk factors for squamous cell carcinoma?

SCC shares many risk factors with other skin cancers. While some can be controlled, others cannot.

Squamous cell carcinoma risk factors that can be controlled

Several key risk factors for SCC can be managed. Most notably, exposure to UV radiation from the sun or indoor tanning devices is a well-established risk factor for most forms of skin cancer, including squamous cell carcinoma. Practicing sun protection, such as liberally applying sunscreen and wearing protective clothing outdoors, can help reduce the risk.

Other controllable risk factors for SCC include:

• Human papillomavirus (HPV) – Persistent HPV infection, particularly with a high-risk strain such as HPV-16 or HPV-18, significantly increases the likelihood of developing squamous cell carcinoma. In addition to practicing safe sex, receiving an HPV vaccination, such as Gardasil, is an effective way to prevent HPV-related cancers.
• Tobacco use – Smoking significantly increases the risk of squamous cell carcinoma, particularly in the head, neck and lungs. Quitting tobacco can greatly reduce this risk over time.
• Alcohol consumption – Heavy or frequent drinking can increase the risk of squamous cell carcinoma, especially in the mouth, throat and esophagus. Limiting alcohol intake can lower the risk.

Squamous cell carcinoma risk factors that cannot be controlled

Some risk factors for SCC cannot be managed. These include:

• Advanced age – Skin cancer risk increases with age, mainly due to cumulative exposure to UV rays and other risk factors over time.
• Fitzpatrick skin type 1 or 2 – Individuals with light-colored hair and eyes and fair skin that burns easily and tans minimally (type 1) or burns easily but tans slightly (type 2) are more likely to sustain UV light-induced cell damage due to a lack of skin pigment (melanin), which provides some level of protection against skin cancer.
• Genetic predisposition – A family history of skin cancer can increase the risk of squamous cell carcinoma.
• Phototherapy – Light-based treatments for psoriasis, dermatitis and other inflammatory skin conditions involve strategically exposing the skin to UV rays in a medical setting.
• Sunlight sensitivity – Individuals who take photosensitizing medications, such as certain antibiotics and antihistamines, and those who have a photosensitive medical condition, such as lupus, are at heightened risk.
• Weakened immune system – Individuals with a weakened immune system, including those with human immunodeficiency virus (HIV) and those who are taking immunosuppressants to reduce the risk of rejection after an organ transplant, are at elevated risk.

Can squamous cell carcinoma be prevented?

Like other skin cancers, SCC can occur with no known risk factors. Still, it is important to take proactive steps to manage the risk factors that are known to be controllable. Effective preventive strategies include:

• Limiting sun exposure
• Avoiding indoor tanning devices
• Protecting the skin from UV light
• Avoiding tobacco
• Limiting alcohol consumption
• Receiving an HPV vaccine

Additionally, early detection of unusual skin changes plays a key role in squamous cell carcinoma prevention. With regular self-exams and professional skin cancer screenings, it may be possible to identify atypical skin variations early, allowing for prompt intervention if needed and greatly increasing the likelihood of effective treatment and cure.

Frequently asked questions (FAQs) about squamous cell carcinoma causes and risk factors

The following FAQs-related article provides additional information about SCC causes and risk factors:

• What causes squamous cell carcinoma?

Benefit from world-class care at Moffitt Cancer Center

As a nationally recognized leader in squamous cell carcinoma research, Moffitt is actively involved in clinical trials to investigate the precise mechanisms behind the development of skin cancer and evaluate more effective ways to treat it. In recognition of our progress to date, the National Cancer Institute has designated Moffitt a Comprehensive Cancer Center. Our goal is to quickly bring our groundbreaking laboratory discoveries from bench to bedside, allowing our patients to benefit as soon as possible.

If you would like to learn more about squamous cell carcinoma causes and risk factors, you can request an appointment with a specialist in our Cutaneous Oncology Program by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.