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Skin Cancer (Squamous Cell Carcinoma) – A Comprehensive Medical Guide

Overview

Squamous cell carcinoma (SCC) is the second‑most common type of non‑melanoma skin cancer, arising from the squamous cells that compose the outer layer of the epidermis. While it accounts for roughly 20–25% of all skin cancers, its incidence has been rising steadily—in the United States, more than 1.8 million new cases of non‑melanoma skin cancer are diagnosed each year, and SCC makes up about 400,000 of those cases.

Who it affects: Anyone can develop SCC, but it is most common in adults over age 50, people with fair skin (especially those who burn easily), and individuals with a history of chronic sun exposure. Men are slightly more likely than women to develop SCC, and the risk increases with cumulative UV exposure.

Geographic prevalence: Rates are highest in regions with intense UV radiation, such as the southern United States, Australia, and parts of Southern Europe. According to the World Health Organization, the global burden of non‑melanoma skin cancer is expected to exceed 3 million new cases per year by 2030 if current trends continue.

Symptoms

Squamous cell carcinoma often appears as a solitary lesion, but multiple lesions can arise, especially in immunocompromised patients. Common presentations include:

• Red, scaly patch (erythematous plaque) – may feel rough or sandpaper‑like.
• Firm, raised nodule – can be flesh‑colored, pink, or brown.
• Open sore (ulcer) that bleeds or crusts – may persist for weeks.
• Warty growth – resembles a common wart but does not resolve.
• Flat, scar‑like lesion – can be mistaken for a scar or eczema.
• Rapid growth – lesions that enlarge within weeks warrant prompt evaluation.
• Pain or tenderness – especially if the tumor invades deeper tissue.
• Itching or burning sensation – common in lesions on the hands, forearms, or face.

Typical locations: sun‑exposed areas such as the face (especially the nose and ears), scalp, neck, lips, hands, forearms, and, in men, the lower legs. Chronic wounds, scars, or areas of previous radiation therapy can also give rise to SCC (called Marjolin ulcer).

Causes and Risk Factors

Primary cause – Ultraviolet (UV) radiation

UV‑B (280–315 nm) directly damages DNA in skin cells, creating pyrimidine dimers that trigger mutations in tumor‑suppressor genes (e.g., TP53). Over time, these mutations accumulate and can transform normal keratinocytes into malignant SCC cells.

Additional contributors

• Age – cumulative UV damage builds over decades.
• Fair skin, red or blond hair, blue/green eyes – less melanin provides less natural protection.
• History of sunburns, especially blistering burns before age 20.
• Chronic immunosuppression (organ transplant recipients, HIV, long‑term corticosteroids) – immunosurveillance is weakened, increasing SCC risk up to 65‑fold.
• Human papillomavirus (HPV) infection – particularly HPV‑16 and HPV‑23 in the genital or peri‑anal region.
• Exposure to chemical carcinogens such as arsenic, industrial tar, or polycyclic aromatic hydrocarbons.
• Radiation therapy – prior therapeutic radiation can create SCC years later.
• Chronic wounds or scars – the long‑standing inflammation promotes malignant change.

Who is at highest risk?

According to the American Cancer Society, the following groups have the greatest likelihood of developing SCC:

1. Men over 50 with a history of outdoor occupations (e.g., construction, farming).
2. Organ‑transplant recipients (especially kidney, heart, liver).
3. Individuals with a prior diagnosis of basal cell carcinoma or another SCC.
4. People with chronic inflammatory skin conditions such as lichen planus or lupus.

Diagnosis

Early detection improves outcomes dramatically. Diagnosis typically involves a combination of visual examination, dermoscopic evaluation, and a tissue biopsy.

Clinical evaluation

• History taking – duration, changes, prior sun exposure, immunosuppression, previous skin cancers.
• Physical examination – inspection of the lesion, assessment of regional lymph nodes.

Dermatoscopy

Using a handheld dermatoscope can reveal characteristic vascular patterns (glomerular vessels) and scaling that help differentiate SCC from benign lesions.

Skin biopsy (definitive diagnosis)

• Punch biopsy – 4–6 mm core of tissue, most common.
• Excisional biopsy – complete removal of small lesions, both diagnostic and therapeutic.
• Incisional biopsy – for large or poorly defined lesions.

The specimen is examined histologically for atypical keratinocytes, keratin pearls, and invasion depth (Breslow thickness). Pathology reports also note perineural involvement, which affects treatment planning.

Imaging (when indicated)

If there is suspicion of deep invasion, regional spread, or metastasis, additional studies may be ordered:

• Ultrasound of regional lymph nodes.
• CT or MRI for head and neck lesions.
• Positron emission tomography (PET) for high‑risk or recurrent disease.

Treatment Options

Treatment is individualized based on tumor size, location, depth, patient comorbidities, and cosmetic considerations. Most SCCs are curable when treated early.

Standard surgical approaches

• Excisional surgery – removal with 4–6 mm margins for low‑risk tumors; 6–10 mm for high‑risk.
• Mohs micrographic surgery – layer‑by‑layer removal with immediate microscopic examination; highest cure rate (>99% for primary lesions) and tissue conservation, ideal for the face, ears, and areas where cosmetic outcome is critical.
• Curettage and electrodesiccation – for small, low‑risk lesions (<1 cm) on low‑cosmetic‑impact sites.

Non‑surgical therapies

• Radiation therapy – external beam radiation for patients who are poor surgical candidates or for peri‑ocular/ear lesions where surgery would be disfiguring.
• Topical chemotherapy – 5‑fluorouracil (5‑FU) cream for superficial SCC in situ (Bowen disease).
• Photodynamic therapy (PDT) – photosensitizing agent (e.g., aminolevulinic acid) activated by light; useful for superficial tumors.
• Systemic therapy – for locally advanced or metastatic SCC:
  • Immunotherapy: PD‑1 inhibitors such as cemiplimab or pembrolizumab have demonstrated response rates of 40‑50% in advanced SCC (FDA‑approved 2018).
  • Targeted therapy: EGFR inhibitors (cetuximab) are occasionally used, though data are limited.

Adjuvant treatment

High‑risk features (perineural invasion, deep >6 mm, or positive margins) may warrant postoperative radiation or systemic therapy to reduce recurrence.

Lifestyle & supportive measures

• Smoking cessation – tobacco impairs wound healing and increases recurrence.
• Optimizing nutrition (adequate protein, vitamins A, C, E) to support skin repair.
• Regular follow‑up skin examinations every 6–12 months.

Living with Skin Cancer (Squamous Cell Carcinoma)

Post‑treatment skin care

• Keep the wound clean and apply physician‑prescribed ointments.
• Use silicone gel sheets or pressure garments if scarring is a concern.
• Avoid sun exposure to the healing area for at least 4–6 weeks—apply broad‑spectrum sunscreen (SPF 30 or higher) and wear protective clothing.

Self‑examination routine

Perform a full‑body skin check once a month. Look for new lesions, changes in existing moles, or any persistent sores that do not heal within 2–3 weeks.

Psychosocial considerations

• Many patients experience anxiety about recurrence; counseling or support groups (e.g., American Cancer Society “Skin Cancer Survivors”) can be helpful.
• Address cosmetic concerns early—consult a dermatologist or plastic surgeon for reconstructive options.

Follow‑up schedule

Typical follow‑up includes:

• First visit 2–4 weeks post‑procedure to assess healing.
• Every 3–6 months for the first 2 years (highest risk period).
• Annually thereafter, or more frequently if you have risk factors (immunosuppression, prior multiple SCCs).

Prevention

Because UV exposure is the dominant modifiable risk, primary prevention focuses on protection and early detection.

• Sun‑smart behaviors: Seek shade, avoid peak sun (10 am–4 pm), and wear wide‑brim hats, UPF clothing, and UV‑blocking sunglasses.
• Sunscreen use: Apply a broad‑spectrum SPF 30+ sunscreen 15 minutes before outdoor activity; reapply every 2 hours, and after swimming or sweating.
• Regular skin exams: Annual dermatologist visits for high‑risk individuals (fair skin, prior skin cancer, immunosuppressed).
• Smoking cessation: Reduces overall cancer risk and improves skin health.
• Protect occupational exposure: Use protective clothing and sunscreen for outdoor workers; employers should provide sunscreen stations.
• Manage chronic wounds: Ensure proper wound care, reduce inflammation, and have any non‑healing ulcer biopsied promptly.
• Vaccination: HPV vaccination can lower the risk of HPV‑related SCC, especially in the anogenital region.

Complications

If left untreated or inadequately treated, SCC can progress to more serious conditions:

• Local invasion – into deeper dermis, muscle, cartilage, or bone, leading to functional impairment (e.g., loss of ear cartilage).
• Perineural spread – tumor follows nerve pathways, causing pain, numbness, or facial paralysis.
• Regional metastasis – spread to nearby lymph nodes, especially in high‑risk head‑and‑neck SCC.
• Distant metastasis – uncommon (<5%) but can involve lungs, liver, or brain, dramatically worsening prognosis.
• Recurrence – up to 8% for low‑risk lesions; higher for tumors with positive margins, deep invasion, or immunosuppression.
• Functional and cosmetic deficits – especially after extensive surgery on the face or extremities.

When to Seek Emergency Care

References

• Mayo Clinic. Squamous cell skin cancer – Symptoms & causes. Accessed April 2026.
• American Cancer Society. What Is Squamous Cell Carcinoma?. Updated 2025.
• Centers for Disease Control and Prevention. Skin Cancer Statistics. 2024.
• National Cancer Institute. PDQ – Squamous Cell Skin Cancer Treatment. Reviewed 2023.
• Cleveland Clinic. Squamous Cell Carcinoma of the Skin. 2024.
• Food and Drug Administration. FDA approves cemiplimab for advanced SCC. 2018.
• World Health Organization. Skin cancers fact sheet. 2023.

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