Basal cell carcinomas are the most common and the least dangerous form of skin cancer. They account for about three-quarters of all skin cancer cases and are particularly common in New Zealand and Australia. These cancers almost never spread to other parts of the body (metastasise). However, if left untreated, they can cause damage by growing very large and can invade surrounding tissue.

Basal cell carcinomas are growths (tumours) that occur in the basal cells of the epidermis (the top-most layer) of the skin. Basal cells are found in the deepest layers (the base) of the epidermis. There are several different types of basal cell carcinoma, and each type looks different. Sometimes they look like non-cancerous skin conditions such as eczema or psoriasis.

The most common forms are:

  • a pink or red patch of scaly skin, which can be mistaken for patches of dermatitis or eczema
  • an open sore that doesn’t heal
  • a shiny bump that is pearly or translucent
  • a pink growth
  • a shiny and tight scar-like area.

Nature of Science

Scientists work in many different fields. Some scientists observe space through a telescope while others observe cells through a microscope.

The Sun is responsible for over 90 percent of all skin cancers including basal cell carcinomas, so they are usually (but not always) found on areas of the body that are exposed to the Sun such as the face, ears, back of the hands, arms and shoulders. Research shows that it is specifically the UVB rays that cause basal cell carcinomas.

Are basal cell carcinomas life-threatening?

Basal cell carcinomas do not often cause death. This is because they are not usually invasive – they very rarely spread to other parts of the body – so it is extremely rare for basal cell carcinomas to affect the lymph nodes or blood. In fact, only 230 cases of metastasising have ever been reported in New Zealand. However, if it is not treated, it can grow very large, be very, very disfiguring and can totally destroy local tissue, for example, ears, noses, eyelids, lips, nerves, cartilage or bone.

Because basal cell carcinomas are not invasive metastasising cancers, they are not required to be reported and registered by doctors. That also means that they are not included in our national cancer statistics. It is estimated that there are between 45,000 (confirmed by laboratory tests) and 70,000 instances of basal cell carcinoma each year in New Zealand.

How is basal cell carcinoma treated?

Treatment varies depending on the size, depth and location. The most common treatment is surgical removal – the earlier the better. Other treatment options include scraping out, freezing and radiation.

Useful links

Description and images of each type of basal cell carcinoma.
www.skincancer.org

    Published 29 July 2008