What causes bcc cancer

Overview

Basal cell carcinoma (BCC) is the most common type of skin cancer worldwide. It originates in the basal cells, which are found in the lower part of the epidermis, the outermost layer of the skin. These cells are responsible for producing new skin cells as old ones die. BCCs typically develop on skin that has been exposed to the sun over many years, particularly on areas like the face, ears, neck, scalp, shoulders, and back.

Fortunately, BCCs are usually slow-growing and rarely spread (metastasize) to other parts of the body. When detected and treated early, they have a very high cure rate. However, if left untreated, they can grow deep into the skin, damaging surrounding tissue and bone, and can become disfiguring.

What Causes Basal Cell Carcinoma?

The primary cause of basal cell carcinoma is damage to the DNA of basal skin cells, which is overwhelmingly caused by exposure to ultraviolet (UV) radiation. This damage occurs over years of exposure, accumulating to the point where the cells' ability to repair themselves is overwhelmed, leading to uncontrolled growth.

Ultraviolet (UV) Radiation Exposure

The sun is the most significant source of UV radiation. When your skin is exposed to UV rays, they penetrate the skin and can damage the DNA within the cells. While your body has mechanisms to repair this damage, repeated and prolonged exposure can lead to permanent mutations in the DNA of basal cells. These mutations can cause the cells to grow abnormally and form tumors.

• Cumulative Sun Exposure: The total amount of time spent in the sun throughout your life is a major factor. Even if you don't get severe sunburns, years of moderate sun exposure can increase your risk.
• Intermittent Sun Exposure and Severe Sunburns: While cumulative exposure is key, episodes of intense sun exposure leading to sunburns, especially during childhood and adolescence, also significantly increase the risk of BCC. These sunburns can cause acute DNA damage that contributes to cancer development later in life.
• Geographic Location and Altitude: Living in sunny climates or at higher altitudes, where UV radiation is more intense, increases exposure and thus risk.

Artificial UV Sources

Tanning beds and sunlamps are also sources of UV radiation and are strongly linked to an increased risk of BCC. Many health organizations advise against their use due to the significant cancer risk they pose. The UV radiation emitted by tanning devices is often more intense than that of the sun.

Risk Factors

While UV exposure is the primary cause, certain factors can increase an individual's susceptibility to developing BCC:

• Skin Type: People with fair skin that burns easily, freckles, light-colored eyes (blue or green), and blond or red hair are at higher risk because their skin has less melanin, the pigment that offers some protection against UV damage.
• Age: The risk of BCC increases with age, as cumulative sun exposure builds up over time. Most BCCs occur in people over the age of 50, but they can also affect younger individuals, especially those with significant sun exposure history.
• History of Skin Cancer: Individuals who have had BCC or other types of skin cancer are at a higher risk of developing new skin cancers, including BCC.
• Weakened Immune System: People with compromised immune systems due to medical conditions (like HIV/AIDS) or immunosuppressant medications (such as those used after organ transplants) are more prone to developing skin cancers, including BCC.
• Exposure to Certain Chemicals: Exposure to arsenic has been linked to an increased risk of skin cancer, including BCC.
• Radiation Therapy: Previous radiation treatment for other medical conditions can increase the risk of developing skin cancer in the treated area.
• Genetic Predisposition: Certain rare genetic syndromes, such as Gorlin syndrome (nevoid basal cell carcinoma syndrome), can cause individuals to develop numerous BCCs from a young age.

How UV Damage Leads to BCC

UV radiation damages the DNA in the basal cells. Specifically, UV radiation causes characteristic mutations in genes that control cell growth and division, such as the tumor suppressor gene PTCH1. When these genes are mutated, they can no longer effectively regulate cell proliferation. As a result, the basal cells begin to grow and divide uncontrollably, forming a tumor. The body's natural repair mechanisms are often unable to correct the extensive damage, leading to the development of a cancerous growth.

It's important to understand that the damage is cumulative. Every time you expose your skin to UV radiation without adequate protection, you increase your risk. Prevention through sun safety measures is the most effective way to reduce the likelihood of developing basal cell carcinoma.