Exposure to ultraviolet (UV) light is one of the most common causes of skin cancer, and it can lead to a deadly form of skin cancer known as melanoma.
Like other forms of cancer, skin cancer is caused by cells mutating and growing out of control, creating dangerous tumors instead of healthy skin cells. Many skin cancer sites begin as moles, though not all moles develop into cancer.
But what are the causes of skin cancer mutations that happen in the first place?
Our genes control what happens within our cells. Genes that triggers cells to divide and grow are known as oncogenes, while those that control cell growth or cause cells to die at the right time are called tumor suppressor genes. Factors in your lifestyle, environment, or personal health can either turn on oncogenes or turn off tumor suppressor genes. When this happens, healthy skin cells begin to mutate and turn into skin cancer.
Ultraviolet light exposure causes skin cancer
Exposure to ultraviolet (UV) light is one of the most common causes of skin cancer, and it can cause a deadly form of skin cancer known as melanoma. UV rays damage the DNA in skin cells, causing mutations and triggering the growth of cancer cells.
Most ultraviolet light comes from sun exposure. However, the light in tanning beds is also a major cause of skin cancer. The Centers for Disease Control and Prevention (CDC) estimates that UV exposure from tanning beds causes around 400,000 deaths from skin cancer in the United States every year.
Tanning or burning are particularly dangerous, but any amount of unprotected sun exposure can cause skin cancer. Many times, the damage caused by exposure to ultraviolet light occurs years before cancer cells appear. Sunburns during childhood and adolescence can develop into skin cancer well into adulthood.
Though people with light skin and red or blonde hair are at the highest risk for burning as a result of UV exposure, any color skin can be damaged by ultraviolet radiation and develop skin cancer. Even those with dark skin that never burns are at risk for skin cancer as a result of UV exposure.
Genetic risks for skin cancer
Inherited genetic changes can also cause melanomas and nonmelanoma skin cancers: squamous cell cancers and basal cell carcinomas.
Inherited melanomas run in families and are generally due to a change in CDKN2A, a tumor suppressor gene. Squamous cell cancers are often caused by changes in the gene TP53.
Genetic conditions can also cause skin cancer. Basal cell nevus syndrome, also known as Gorlin syndrome, runs in families and alters the PTCH1 gene in all the body’s cells. This change often causes people with Gorlin syndrome to develop many basal cell cancers.
Xeroderma pigmentosum, or XP, is another inherited condition that can cause skin cancer. People with XP have a defect in the enzyme that repairs their cells’ DNA. As a result, their skin is less able to recover from sun damage and more prone to developing skin cancer.
Skin cancer is just one of many forms of cancer that has inherited genetic causes. As with other types of cancer, however, genetic causes of skin cancer can sometimes be targeted with new drugs and treatments. Melanomas, for example, often contain changes in the BRAF oncogene, which can be treated with targeted tumor therapy.
Other causes of skin cancer
Factors in your immediate environment can cause skin cancer, including exposure to pollutants, chemical carcinogens, and environmental radiation. Research has found that lifestyle factors such as diet and smoking can also make you more likely to develop skin cancer, though there are usually other causes contributing to the cancer’s development, such as sun exposure.
Skin with existing damage, such as scars, ulcers, burns, or nonhealing wounds, is more susceptible to cancer growth, especially if these spots are regularly exposed to UV light or environmental carcinogens.
Because your immune system plays a role in fighting the growth of cancer cells, conditions that suppress your immune system can cause skin cancer. These include human immunodeficiency virus (HIV), acquired immune deficiency syndrome (AIDS), and some non-Hodgkin’s lymphomas. Immunosuppression drugs, such as those given to organ transplant patients, can also put you at risk for developing skin cancer.
Preventing skin cancer
Skin cancer is one of the most commonly diagnosed cancers in the United States, with nearly 5 million Americans being treated for some form of skin cancer every year.
According to the U.S. Surgeon General, most cases of skin cancer are preventable if you protect yourself from environmental causes. This includes avoiding tanning, both in sunlight and in artificial UV light, wearing sun protection outside, and avoiding environmental and workplace toxins such as arsenic and pollution. While medical and genetic causes of skin cancer are not preventable, protecting yourself from everyday causes will greatly reduce the chance that you develop skin cancer in your lifetime.
June 13, 2017
Christopher Nystuen, MD, MBA