The course of non-melanoma skin cancer

Photo of a woman looking at the skin on her arm (PantherMedia / Edyta Guhl) 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. Most of these tumors are discovered before they spread 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 during surgery. 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 is also most common in older people. The average age of those who have this disease is 70. 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 your hands.

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 usually 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 it 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 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. It typically affects older people who live in regions with strong sunlight. Actinic keratosis generally appears on several areas of skin. The affected skin is reddish or brown in color, rough and scaly, and sometimes thicker than normal skin. It may have “pointy” bumps on it.

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 (intra-epidermal squamous cell carcinoma) is characterized by a clearly defined reddish, scaly patch of skin. It develops into squamous cell carcinoma in about 3 out of 100 people. This kind of tumor is fairly aggressive and often spreads to other parts of the body.