The course of non-melanoma skin cancer

Photo of a woman looking at the skin on her arm

There are two main types of non-melanoma skin cancer, known as basal cell carcinoma and squamous cell carcinoma. Basal cell carcinoma is the most common kind of skin cancer, but it usually grows slowly. Squamous cell carcinoma is somewhat more aggressive. Non-melanoma skin cancer is usually discovered before it spreads to other parts of the body, though.

Basal cell carcinoma

Basal cell carcinoma (basal cell cancer) mainly affects people over the age of 60 and is most commonly found on the face, neck or other parts of the head that are regularly exposed to sunlight. It usually grows slowly and stays in the area where it first developed. So it's generally discovered at a stage where it can still be completely removed with a small surgical procedure. But it's not totally harmless: If it's only treated very late, or not treated at all, it can enter deeper layers of tissue. This can cause damage to things like your nose, eyes and facial bones.

Because basal cell carcinoma rarely spreads to other parts of the body (metastasis), it is rarely fatal: Only about 1 out of 1,000 people who have basal cell cancer die of it.

Squamous cell carcinoma

Squamous cell carcinoma (squamous cell cancer) is also most common in older people. The average age of those who have this disease is 70. In people with light skin, it nearly always develops on parts of the body that are exposed to the sun – especially on the face, ears, lower lip and the back of the hands. In people with dark skin, it often affects areas that are usually covered by clothing, such as the legs and genital area.

Like basal cell carcinoma, squamous cell carcinoma grows where it first developed, damaging nearby tissue. But it is more aggressive than basal cell carcinoma – particularly if it grows in an old scar, a sore, or on your lips or ears.

If left untreated, there is a danger that the cancer might spread to other parts of the body. Squamous cell carcinoma is usually detected before it spreads, though. Then it is normally quite easy to treat. About 40 to 50 out of 1,000 people with squamous cell carcinoma die of it.

People who have had skin cancer in the past are more likely to get skin cancer in the future. If skin cancer comes back, it may be more aggressive than it was the first time.

Pre-cancerous conditions: Actinic keratosis and Bowen’s disease

Squamous cell carcinoma usually develops from abnormal cells due to skin conditions such as actinic keratosis or Bowen’s disease. These pre-cancerous conditions are treated in order to prevent cancer from developing.

Actinic keratosis (also called solar keratosis or senile keratosis) arises if skin is constantly exposed to the sun, becoming thicker and harder as a result. Then the affected area feels rough, like a callus. The skin there is reddish or brownish in color, rough and flaky, and sometimes thicker and raised. It nearly always develops on parts of the body that are exposed to the sun a lot – for example, on the face or on the scalp (if there's no hair covering it). Actinic keratosis generally appears on several areas of skin. It typically affects older people who live in regions with strong sunlight.

It is very difficult to say whether actinic keratosis will go away or develop into cancer. Doctors generally suggest having treatment to remove the abnormal tissue.

Bowen’s disease looks like a clearly defined patch of crusted skin. In people with light skin, the patch is reddish in color. On darker skin it is usually dark, but it may also be lighter than the surrounding healthy skin. Bowen's disease develops into squamous cell carcinoma in about 3 out of 100 people. This kind of skin cancer is fairly aggressive and often spreads to other parts of the body.

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Dadzie OE, Petit A, Alexis AF. Ethnic Dermatology: Principles and Practice. Hoboken: Wiley-Blackwell; 2013.

Gloster HM, Neal K. Skin cancer in skin of color. J Am Acad Dermatol 2006; 55(5): 741-760; quiz 761-744.

Hogue L, Harvey VM. Basal Cell Carcinoma, Squamous Cell Carcinoma, and Cutaneous Melanoma in Skin of Color Patients. Dermatol Clin 2019; 37(4): 519-526.

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IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

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Updated on February 19, 2024

Next planned update: 2027

Publisher:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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