Skin cancer is the abnormal, uncontrolled growth of skin cells. It is the most common cancer globally and especially prevalent in countries with high sun exposure. In the United States, approximately one in five Americans will develop skin cancer by the age of 70. Understanding how skin cancer develops, recognizing its signs, and knowing the risk factors are crucial in early diagnosis and prevention.

Types of Skin Cancer

Skin cancer is categorized based on the type of skin cell involved. The most common types are nonmelanoma skin cancers, which include basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), and the more aggressive melanoma. Rare types include Merkel cell carcinoma and others like Kaposi sarcoma and cutaneous lymphoma.

  • Basal Cell Carcinoma (BCC): BCC accounts for roughly 80-90% of all skin cancer cases. It develops from the basal cells in the lowest layer of the epidermis and typically grows slowly. It rarely spreads to other parts of the body but can cause local tissue damage if not treated.
  • Squamous Cell Carcinoma (SCC): SCC is the second most common type. It originates in the flat, scale-like cells above the basal layer of the skin. SCC may spread if not addressed promptly, especially in immunocompromised individuals.
  • Melanoma: Though less common, melanoma is far more dangerous. It begins in melanocytes—the pigment-producing cells in the skin—and can rapidly spread to other parts of the body.
  • Merkel Cell Carcinoma: A rare and aggressive cancer arising from Merkel cells in the epidermis. It is more common in older adults and those with weakened immune systems.

Recognizing the Signs

Skin cancer can present in a variety of forms and appearances. While it commonly affects sun-exposed areas like the face, ears, neck, scalp, and arms, it can also appear in less visible locations, including under the nails or inside the mouth.

General signs include:

  • New growths or lumps
  • Changes in existing moles
  • Sores that don’t heal
  • Patches that crust, bleed, or change in texture

Basal Cell Carcinoma signs:

  • Pearly or waxy bump
  • Flat, flesh-colored or brown scar-like lesion
  • Bleeding or oozing sore that doesn't heal

Squamous Cell Carcinoma signs:

  • Scaly red patches
  • Open sores
  • Elevated growths with a central depression
  • Wart-like lesions

Melanoma warning signs:

  • A mole or skin lesion that follows the ABCDE rule:
    • Asymmetry: Uneven shape
    • Border: Irregular or blurred edges
    • Color: Uneven shades including black, brown, and tan
    • Diameter: Greater than 6 mm
    • Evolving: Change in size, shape, or color over time

People with darker skin may develop skin cancer in less typical places, such as the palms, soles, or under the nails. For these populations, melanoma is often diagnosed later, leading to worse outcomes.

Root Causes and Risks

The main cause of skin cancer is overexposure to ultraviolet (UV) radiation from the sun and artificial sources such as tanning beds. UVB rays primarily cause sunburn, while UVA rays contribute to skin aging—but both types can damage DNA in skin cells.

Major risk factors include:

  • Frequent sunburns or prolonged sun exposure
  • Use of tanning beds
  • Fair skin, freckles, red or blonde hair
  • Numerous or atypical moles
  • Family or personal history of skin cancer
  • Older age, though younger individuals are increasingly at risk
  • Immunosuppression (e.g., organ transplant recipients)

Diagnosing Skin Cancer

Diagnosis begins with a clinical skin examination. A healthcare provider may use a dermatoscope to inspect moles or suspicious lesions more closely.

If a lesion appears abnormal, a biopsy is required. Common types include:

  • Excisional biopsy: Entire growth is removed
  • Punch biopsy: A circular tool removes a sample of skin
  • Shave biopsy: Surface layers of skin are shaved off for examination

If melanoma is diagnosed, additional tests such as lymph node biopsy, imaging (CT, MRI, or PET), or blood work may follow to determine if the cancer has metastasized.

Understanding Staging

Staging helps determine how far the cancer has spread and guides treatment.

  • Stage 0 (in situ): Confined to the outermost skin layer
  • Stage I: Tumor is small and localized
  • Stage II: Larger tumor, possibly ulcerated, but still localized
  • Stage III: Spread to nearby lymph nodes or surrounding tissues
  • Stage IV: Cancer has metastasized to distant organs like the lungs or brain

Nonmelanoma skin cancers typically do not require staging unless the case is advanced.

Treatment Options

The choice of treatment depends on the type, size, location, and stage of the cancer.

Common treatments include:

  • Surgery: Most skin cancers are surgically removed. Mohs surgery offers high cure rates by removing cancer layer by layer.
  • Topical Treatments: Creams like imiquimod or fluorouracil may be applied for superficial cancers.
  • Cryotherapy: Involves freezing the cancer with liquid nitrogen.
  • Photodynamic Therapy: Uses a combination of light and photosensitizing agents.
  • Radiation Therapy: Often used for areas that are difficult to operate on or in older patients.
  • Chemotherapy: May be topical or systemic, often reserved for advanced cases.
  • Immunotherapy/Targeted Therapy: Especially for melanoma, drugs like nivolumab or pembrolizumab can stimulate the immune system. BRAF and MEK inhibitors are used for targeted mutations.

How to Stay Protected

Preventing skin cancer largely revolves around minimizing UV exposure:

  • Avoid sun exposure between 10 a.m. and 4 p.m.
  • Apply broad-spectrum sunscreen (SPF 30+) daily and reapply every two hours
  • Wear protective clothing, wide-brimmed hats, and UV-blocking sunglasses
  • Avoid tanning beds
  • Perform monthly skin checks and look for unusual moles or lesions
  • See a dermatologist annually or more frequently if you're high-risk

Associated Complications

Even when successfully treated, skin cancer can lead to complications:

  • Anxiety and Depression: Emotional distress is common. Mental health support is often needed, especially for those with melanoma.
  • Lymphedema: Swelling from lymphatic blockage, often after lymph node removal.
  • Infections: Especially after surgical treatments. Staphylococcus infections are common and may cause redness, swelling, and pain.

Living With Skin Cancer

For most, especially those diagnosed early with BCC or SCC, prognosis is excellent. Melanoma presents greater risks but is highly treatable when caught early. Regular follow-up care and skin monitoring are essential.

Racial disparities exist in melanoma outcomes. People of color often present with later-stage melanoma due to misdiagnosis or lack of awareness. Training programs and resources like the American Academy of Dermatology's Skin of Color Curriculum aim to close this gap.

Awareness and self-advocacy are key. Know your skin, know your risks, and don’t ignore changes.