Overexposure to sunlight, through ultraviolet (UV) radiation, is the main cause of skin cancer. Although UV rays help produce vitamin D, they can also cause skin damage, especially among light-skinned people.
Several additional factors can also increase your chances of developing skin cancer. Although some may be out of your control, it is important to know how to reduce the risk.
1. Biological sex
Men are more likely than women to develop basal cell carcinoma and squamous cell carcinoma, two of the most common and curable types of skin cancer.
In general, men are also more likely to get melanoma, which is the most dangerous form of skin cancer. Although it is more common in women up to age 50, the risk increases in men after that age.
At age 65, men are twice as at risk as women. By age 80, they are three times more likely to have melanoma.
However, the incidence of non-melanoma skin cancers among women has increased at a greater rate than among men.
Reasons why men are more prone to skin cancer may include:
- Thicker skin, with less fat underneath and more collagen and elastin.
- More intense reaction to UV rays.
- Less knowledge about sun protection
2. UV exposure and burns
Intermittent periods of intense UV exposure, the type that causes sunburn, can increase the risk of developing skin cancer. On average, your risk of developing melanoma doubles if you have had five or more sunburns.
If your skin has been damaged by another type of burn, it may also increase your risk.
“A history of a previous burn, not just a sunburn but any burn, is a risk factor for developing skin cancer later,” he says. Kenneth Mark, MDcosmetic dermatologist based in New York and Colorado.
Although UV rays can affect your skin any time you are in the sun, during any time of year, they are often strongest between 10 a.m. and 4 p.m. Your risk of exposure and skin damage increases with the UV index, which shows how strong UV light is in your area.
3. Age
The likelihood of developing skin cancer increases as you age, likely due to the cumulative effect of years of UV exposure on the skin. By age 40, you will have only accumulated 47 percent of the sun exposure you will receive during your lifetime, assuming an average life expectancy of 78 years.
Some research also attributes this trend to better detection of skin cancer and increased awareness of skin problems.
More than 55 percent of new melanoma cases are diagnosed in people age 65 and older, and there are also higher mortality rates among that age group, compared to younger people.
4. Chemical exposure
Exposure to certain chemicals can increase the risk of developing skin cancer.
Long-term exposure to large amounts of arsenic, a natural toxin, is associated with an increased risk of basal and squamous cell skin cancer. It is often found in well water, but can appear everywhere from pesticides to tobacco smoke to brown rice.
Although arsenic can irritate the skin, the most harmful effects come from prolonged exposure to contaminated drinking water.
Being in contact with coal tar, paraffin, and certain types of petroleum can also increase the risk of developing skin cancer.
These may be present in industrial products or pesticides, he says. Howard Sobel, MD, clinical assistant aesthetic dermatologic surgeon at Lenox Hill Hospital in New York City.
5. Medications and treatment
If you have received an organ transplant, you may have up to 100 times the risk of developing skin cancer than those who have not. This is due to the use of immunosuppressive medications to help the body accept the new organ. They help silence the immune system, which can facilitate the growth of cancerous tumors.
Immunosuppressants are also used to combat autoimmune diseases, such as inflammatory bowel disease, lupus, and multiple sclerosis.
If you have a weakened immune system and are concerned about your cancer risk, talk to your doctor about treatment options.
People who undergo radiation therapy for cancer or ultraviolet light therapy may also have an increased risk of developing skin cancer and other types of cancer.
However, radiation therapy is also used to combat basal cell and squamous cell carcinoma. If skin cancer comes back in a place where radiation was given, it is usually not used as treatment again.
Research has found that people who receive high doses of ultraviolet light therapy, or psoralen plus ultraviolet A (PUVA), to treat the skin condition psoriasis over a long period may have an increased risk of developing squamous cell carcinoma. PUVA is considered stronger than a tanning bed, for example. The risk may be lower with therapies such as narrowband ultraviolet B phototherapy, which releases ultraviolet light in a smaller range.
6. Past skin cancer
Having had basal cell carcinoma, squamous cell carcinoma, or melanoma increases the risk of developing these or other skin cancers again.
In fact, up to 43 percent of people who have had skin cancer will see it return, often within two years.
Reasons for recurrence include:
- The same risk factors, such as UV exposure, that contributed to cancer the first time, continue to affect cells. This is why cancer can affect basal cells once and squamous cells another time.
- Treatment or surgery did not remove all cancer cells.
- Increased vigilance in screening, especially if you follow your doctor’s advice about checking your skin for cancer.
Reducing other risk factors, such as UV exposure and smoking, is key to preventing skin cancer from recurring. It is also important to regularly check your skin and have regular screenings with healthcare providers.
7. Other skin problems
Having other skin problems, such as inflamed skin over a bone infection or an inflammatory skin disease, can increase your risk of developing skin cancer over time. This is because these skin problems can promote abnormal cell growth that eventually turns into cancer.
Moles on the skin also increase the risk of developing melanoma. This is especially true among people with 50 or more moles, atypical moles, or large moles.
Although psoriasis is not considered a cause of skin cancer, the same risk factors that contribute to it (as well as treatments that affect the immune system) can also increase skin cancer risks. This is especially true among people with severe cases, as opposed to people with mild psoriasis, due to the greater inflammation involved.
8. Inherited conditions
“Those with a family history of skin cancer are at increased risk.” [of developing skin cancer]” says Dr. Sobel.
Inheriting a condition known as basal cell nevus syndrome, for example, means that numerous basal cell cancers are likely to develop, sometimes beginning in childhood or adolescence.
Other genetic skin conditions that increase the risk of basal cell and squamous cell skin cancers include:
- fanconi anemia
- Epidermolysis bullosa
- Rothmund-Thomson syndrome
- werner syndrome
- flowering syndrome
- Muir-Torre syndrome
As for melanoma, genetic inheritance may account for 5 to 10 percent of all cases, and certain genetic mutations may further increase the risk for women. However, there is not enough research to determine exactly how much genetic conditions increase your risk.
It is also possible to inherit xeroderma pigmentosum, a rare condition that leaves the skin unable to properly repair DNA damage caused by UV exposure. This can also lead to melanoma, especially at a young age.
9. Viruses
Several viruses are linked to an increased risk of skin cancer, often by weakening the immune system.
HIV, the virus that causes AIDS, can cause basal cell and squamous cell cancers.
Some types of human papillomavirus (HPV), especially those that affect the genitals, anus, or the skin around the nails, can cause skin cancer in those areas.
HPV is transmitted through intimate skin-to-skin contact, such as vaginal, oral, or anal sex. It lives in squamous cells, so squamous cell carcinoma is the most common skin cancer that arises from the presence of HPV.
“HPV is linked to squamous cell skin cancer, as well as cervical cancer,” says Dr. Mark. “If you see a visible wart, remove it, freeze it, or treat it topically. If it doesn’t go away, a biopsy is necessary.”
Sobel says other viruses linked to an elevated risk of skin cancer include:
- Merkel cell polyomavirus
- Herpesvirus associated with Kaposi’s sarcoma
- Human T cell lymphotropic virus type 1
- Epstein-Barr virus
10. Smoking
Smoking is considered a risk factor for squamous cell carcinoma, especially on the lips. It is not a known risk factor for basal cell carcinoma or melanoma.
The ingestion of tobacco and smoke causes the consumption of a series of carcinogens. These chemicals can damage cellular DNA and cause the type of cell mutation that helps skin cancer develop.
11. Skin tone
People of all races and ethnicities can develop skin cancer. But people with lighter skin tones are at much higher risk, compared to people with naturally darker skin tones. This is due to the protective qualities of melanin, the natural pigment that gives skin a darker color.
The risk of skin cancer is also higher for people who:
- Freckles appear or burn easily
- Have natural blonde or red hair.
- Have green or blue eyes.
This does not mean that people with darker skin tones cannot get skin cancer. In fact, in darker skin, it is more likely to appear on skin that is not exposed to the sun. Melanoma survival rates are also lower in people with darker skin tones than in those with lighter tones.
12. Use a tanning bed
Although some people use a tanning bed instead of tanning in sunlight, tanning beds can significantly increase the risk of developing skin cancer. Your risk of getting squamous cell carcinoma increases by 58 percent if you use a tanning bed, and your risk of basal cell carcinoma increases by 24 percent.
People ages 20 and younger who use a tanning bed also increase their risk of melanoma by 47 percent. Many states have prohibited young people from accessing tanning beds.
Tanning beds provide exposure to ultraviolet rays in concentrated, harmful doses. They damage skin cells just like the sun does, but often in stronger bursts.
