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Non-melanoma skin cancer

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Precancerous conditions of the skin

Precancerous conditions of the skin have the potential to develop into non-melanoma skin cancer. The most common precancerous conditions of the skin are actinic keratosis and Bowen’s disease.

Actinic keratosis

Actinic keratosis is also called solar keratosis. It is often found on sun-exposed areas of the skin in middle-aged or older people. Actinic cheilitis is a related condition that usually appears on the lower lips. A person with one actinic keratosis will often develop more. The number of actinic keratoses often increases with age. The presence of an actinic keratosis indicates that a person’s skin has suffered sun damage.

Actinic keratoses are considered slow growing. They often go away on their own, but they may come back. Approximately 1% of actinic keratoses develop into squamous cell carcinoma (SCC) if left untreated. Treatment is required because it is difficult to tell which keratoses will develop into cancer.

Risk factors

The following risk factors may increase a person’s chance of developing actinic keratosis:

  • overexposure to ultraviolet B (UVB) radiation from the sun
  • increased age
  • fair skin
  • weakened immune system
  • previous PUVA (psoralen + UVA) therapy

Signs and symptoms

Actinic keratosis is most often seen on skin that is frequently exposed to the sun, such as the face, the backs of hands or a balding scalp. The signs and symptoms of actinic keratosis may include:

  • small, rough patches that may be pink-red or flesh coloured
  • an initially flat surface that becomes slightly raised and wart-like

Diagnosis

Actinic keratosis is diagnosed during an examination of the growth. If it does not go away with treatment or shows signs of developing into SCC, a skin biopsy will be done.

Treatment

Treatment options for actinic keratosis depend on the number and location of keratoses. The treatment may include one or a combination of the following:

  • topical chemotherapy
    • 5-fluorouracil (5-FU, Efudex)
    • ingenol mebutate (Picato)
  • topical biological therapy
    • imiquimod (Aldara or Zyclara)
  • cryosurgery
    • often used on single spots
    • may also be used for many small, raised spots
  • surgery
    • simple surgical excision
    • curettage and electrodesiccation
      • may be used on many large spots
  • chemical peeling
  • laser surgery
  • photodynamic therapy

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Bowen’s disease

Bowen’s disease is an early form of squamous cell carcinoma (SCC). It may be called squamous cell carcinoma in situ. Bowen’s disease involves cancer cells in the epidermis or outermost layer of the skin. Although it can’t spread to the lymph nodes, Bowen’s disease can spread into the deeper layers of the skin if left untreated. When it spreads, it becomes an invasive SCC that then has the potential to spread into the lymph system.

Bowen’s disease may also occur on mucous membranes of the anus and genital skin, such as the penis.

Risk factors

The following risk factors may increase a person’s chance of developing Bowen’s disease:

  • overexposure to ultraviolet B (UVB) radiation from the sun
  • increased age
  • previous radiation therapy
  • weakened immune system
    • Infection with human papillomavirus (HPV) is associated with Bowen’s disease of the anus and genital skin.
  • arsenic exposure

Sign and symptoms

Bowen’s disease is most often seen on the legs, backs of hands, fingers or face. The signs and symptoms of Bowen’s disease may include:

  • a reddish scaly patch, which is sometimes crusted – may be a single patch or multiple areas
  • a windblown appearance of the skin
  • larger, redder and scalier patches than actinic keratoses

Diagnosis

If the signs and symptoms of Bowen’s disease are present, or if the doctor suspects Bowen’s disease, a biopsy will be done to make a diagnosis. The type of biopsy may be:

  • shave biopsy
  • punch biopsy

Treatment

Treatment options for Bowen’s disease depend on the number and location of spots. The treatment may be one or a combination of the following:

  • surgery
    • simple surgical excision
    • curettage and electrodesiccation
  • topical chemotherapy
    • 5-fluorouracil (5-FU, Efudex)
  • topical biological therapy
    • imiquimod (Aldara or Zyclara)
  • cryosurgery
  • photodynamic therapy

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