Notes on...Skin Cancer

Skin cancer is the most common form of cancer globally, primarily caused by uncontrolled growth of abnormal skin cells. The vast majority of cases are linked to excessive exposure to ultraviolet (UV) radiation from sunlight or artificial sources like sun beds. Early detection is crucial for successful treatment and improved outcomes.

Types of Skin Cancer

There are three main types of skin cancer, each originating from different cells within the epidermis (the outermost layer of skin):

  1. Basal Cell Carcinoma (BCC):
    • What it is: The most common type of skin cancer (accounting for about 75% of cases). It originates in the basal cells, found in the lowest part of the epidermis.
    • Appearance: Often presents as a small, shiny, pearly, or waxy bump, sometimes with visible blood vessels. It can also appear as a flat, flesh-coloured or brownish scar-like lesion, or a persistently red, scaly patch. It may bleed, crust, or develop into a painless ulcer that doesn't heal.
    • Behaviour: Typically very slow-growing and rarely spreads to other parts of the body (metastasises). However, if left untreated, it can grow deep into surrounding tissue, bone, and nerves, causing significant local damage.
    • Common Sites: Areas most exposed to the sun, such as the face (especially nose), ears, neck, scalp, shoulders, and back.
  2. Squamous Cell Carcinoma (SCC):
    • What it is: The second most common type (about 20% of cases). It originates in the squamous cells, flat cells in the upper part of the epidermis.
    • Appearance: Often appears as a firm, red nodule; a scaly, crusted patch; or an open sore that doesn't heal. It may be tender to touch and bleed easily.
    • Behaviour: More aggressive than BCC and has a higher risk of spreading (though still relatively low compared to melanoma), especially if left untreated. Can spread to lymph nodes and other parts of the body.
    • Common Sites: Sun-exposed areas like the face, lips, ears, scalp, neck, hands, and arms. Can also develop in areas of chronic inflammation or scarring.
  3. Melanoma:
    • What it is: The most serious and potentially life-threatening type of skin cancer, though it is less common than BCC or SCC. It develops from melanocytes, the pigment-producing cells in the skin.
    • Appearance: Can arise from an existing mole or appear as a new, irregular dark spot on seemingly normal skin. Melanomas often follow the ABCDE rule:
      • Asymmetry: One half of the mole does not match the other.
      • Border irregularity: The edges are ragged, notched, or blurred.
      • Colour variation: The color is uneven, with shades of black, brown, tan, and sometimes red, white, or blue.
      • Diameter: Larger than 6 mm (about the size of a pencil eraser), though melanomas can be smaller.
      • Evolving: The mole is changing in size, shape, colour, elevation, or developing new symptoms like itching, tenderness, or bleeding.
    • Behaviour: Has a high potential to spread rapidly to lymph nodes and other organs if not detected and treated early.
    • Common Sites: Can appear anywhere on the body, including areas not typically exposed to the sun (e.g., soles of feet, palms of hands, under nails). In fair-skinned individuals, common sites include the trunk (men) and legs (women).

Risk Factors

While UV exposure is the primary cause, several factors increase an individual's risk of developing skin cancer:

  • Excessive UV Exposure: History of sunburns (especially blistering ones in childhood), prolonged sun exposure, and frequent use of tanning beds/sunlamps.
  • Fair Skin Type: Pale skin that burns easily, light-coloured eyes (blue, green), and red or blonde hair. Less melanin offers less natural protection.
  • Many Moles or Atypical Moles: A high number of benign moles or moles with unusual features.
  • Family History: A genetic predisposition to skin cancer.
  • Personal History: Previous skin cancer diagnosis significantly increases the risk of recurrence or new cancers.
  • Age: Risk generally increases with age as cumulative sun damage builds up.
  • Weakened Immune System: Due to medical conditions (e.g., HIV) or immunosuppressive medications (e.g., post-organ transplant).
  • Certain Precancerous Lesions: Actinic Keratoses (rough, scaly patches) and Bowen's disease (red, scaly patches) can develop into SCC if untreated.

Prevention: The Most Powerful Defence

Prevention is paramount in minimising the risk of skin cancer.

  • Sun Protection:
    • Seek Shade: Especially between 10 AM and 4 PM when UV rays are strongest.
    • Protective Clothing: Wear wide-brimmed hats, UV-blocking sunglasses, and tightly woven, long-sleeved shirts and long trousers (ideally with UPF rating).
    • Broad-Spectrum Sunscreen: Apply a broad-spectrum SPF 30+ (ideally 50+) sunscreen generously to all exposed skin every single day, even on cloudy days. Reapply every two hours, or more frequently after swimming, sweating, or towel drying.
    • Avoid Tanning Beds/Sunlamps: These emit harmful UV radiation and significantly increase skin cancer risk.
  • Regular Skin Self-Exams: Routinely check your skin from head to toe (including scalp, palms, soles of feet, and between toes) for any new spots, moles that are changing in size, shape, colour, or texture, or any non-healing sores.
  • Professional Skin Checks: Schedule annual skin examinations with a dermatologist, especially if you have risk factors or a history of skin cancer.

Treatment Options

If skin cancer is diagnosed, treatment options vary depending on the type of cancer, its size, location, and whether it has spread. Early detection usually leads to simpler and more effective treatments.

  • Surgical Excision: The most common treatment. The cancer and a margin of healthy tissue around it are cut out.
  • Mohs Micrographic Surgery: A specialised technique where layers of skin are removed one at a time and examined under a microscope until all cancer cells are gone. This preserves as much healthy tissue as possible, ideal for sensitive areas like the face.
  • Curettage and Electrodessication: The cancer is scraped off (curettage) and then the base is cauterised with an electric current to destroy remaining cancer cells.
  • Cryosurgery: Freezing the cancer cells with liquid nitrogen.
  • Radiation Therapy: Uses high-energy rays to kill cancer cells, often used for larger cancers, difficult-to-treat areas, or in patients who cannot undergo surgery.
  • Topical Chemotherapy (e.g., 5-Fluorouracil cream): Applied directly to the skin for certain superficial skin cancers or precancerous lesions.
  • Photodynamic Therapy (PDT): Involves applying a light-sensitising drug to the skin, which is then activated by a specific light source to destroy cancer cells.
  • Targeted Therapy/Immunotherapy: For advanced melanoma or certain aggressive non-melanoma skin cancers, these newer treatments use drugs to target specific cancer cell pathways or boost the body's immune system to fight the cancer.

Consulting with a medical professional is paramount for accurate diagnosis, appropriate treatment selection, and ongoing management of skin cancer. Diligence in prevention and self-monitoring remains the most powerful tools in safeguarding long-term skin health.