There are a number of causes that have been linked to basal cell carcinoma, but the major factor seems to be ultraviolet light (UVB), in the form of sunlight. Other causes of basal cell carcinoma include genetic, or other causes such as pre-existing growths. Overall, though, it seems that no one cause is enough to cause a basal cell carcinoma, and it is likely that a combination of factors ultimately lead to them forming.

Sunlight

Sunlight has been strongly linked to the formation of basal cell carcinoma, as well as other forms of skin cancer. In the case of basal cell carcinoma, it seems to be mostly linked to a long-term effect, due to sun exposure from many years before; it is common to see people with a basal cell carcinoma that only really had their excess exposure 20 or 30 years before. This can have been from sunbathing, but may also have been from everyday exposure (a common example is people who served in the forces and were sent for a few years to hot countries). Unfortunately, it used to be thought many years ago that sunlight was ‘good for you’, so people often strived for a ‘healthy tan’ – it’s only later that we are seeing the damage caused by this sun exposure in the form of a basal cell carcinoma. Dark tans are also unfortunately seen amongst many cultures as being desirable, and the incidence of skin cancer amongst younger age groups is rising accordingly.

Whilst sunbathing is an obvious way to get too much sun, there are many other ways which are often overlooked. Many jobs involve outside work, which include trades such as building. Also, hobbies such as gardening, golf and fishing will lead to long hours in the sun, which can eventually lead to the formation of a basal cell carcinoma.

It is easy to conclude from this that, if the damage has already been done, then surely it’s too late to change things? Well yes and no – yes, the basal cell carcinoma that has already formed will not go away, and will need treating. But, we know that having had one basal cell carcinoma makes you at greater risk of forming more; the advice therefore to anyone that has had a basal cell carcinoma (and in fact the advice to all people) is to avoid excess sun exposure. It is perfectly fine to continue with your hobbies such as gardening and golf, but use sun protection when needed.

Genetic causes

Probably the best known genetic causes of basal cell carcinoma are Gorlin’s syndrome and Xeroderma Pigmentosum (XP).

Gorlin’s syndrome is a genetic condition that affects approximately 1 in 30,000 people. It is caused by a mutation in the PTCH1 gene, which usually makes a protein called ‘patched-1’. Gorlin’s syndrome can cause features such as fibromas (benign growths) in the heart and ovaries, small pits on the palms, and a prominent forehead. It can also cause numerous basal cell carcinomas, which may start appearing at a relatively early age (before 30 years old). Some patients with Gorlin’s syndrome may find that they don’t form many basal cell carcinomas, but others can literally have hundreds growing through their lifetime. Surgery or other treatments such as curettage are still the usual treatment for the basal cell carcinomas, although newer treatments such as the drug ‘Vismodegib’ are proving to have a promising role in Gorlin’s syndrome.

Xeroderma Pigmentosum (XP) affects approximately 1 in a million people, and causes extreme sensitivity to sunlight. XP is caused by gene mutations that lead to problems in repairing damaged DNA. DNA can be damaged by sunlight, and in XP exposure to sunlight can cause dry skin (Xeroderma) and skin pigmentation (Pigmentosum). XP also greatly increases the risk of forming skin cancers, including basal cell carcinoma, which can form in childhood.

Other causes

A number of other factors have been associated with basal cell carcinoma, including diet, tobacco, soot and previous burns. Immunosuppession is also an important cause of basal cell carcinoma, and can affect people with HIV or those taking medication for organ transplants or forms of arthritis.

This information is provided for general knowledge only and does not replace information provided by healthcare professionals. If you have any concerns of any skin growth, you should consult a medical professional urgently. Please also read our disclaimer.