Overexposure to light from the sun, via ultraviolet (UV) radiation, is the main cause of skin cancer. Although UV rays help produce vitamin D, they can also lead to skin damage, especially among people with light skin.
A number of additional factors can increase your chances of developing skin cancer as well. Although some may be out of your control, it’s important to know how to reduce your risk.
1. Biological Sex
Men are more likely than women to develop basal cell carcinoma and squamous cell carcinoma, two of the more common and curable types of skin cancer.
Overall, men are also more likely to get melanoma, which is the most dangerous form of skin cancer. Although it is more common in women until age 50, the risk increases for men after that age.
By age 65, men have double the risk of women. By age 80, they are three times as likely to have melanoma.
The incidence of nonmelanoma skin cancers among women has increased at a higher rate than among men, however.
Reasons for men being more prone to skin cancer may include:
- Thicker skin, with less fat beneath it 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 kind that causes sunburn, may increase your 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 also may increase your risk.
“A history of a prior burn, not only sunburn but any burn, is a risk factor for later developing skin cancer,” says Kenneth Mark, MD, a cosmetic dermatologist based in New York and Colorado.
Although UV rays can affect your skin any time it is exposed to the sun, during any time of year, they often are 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 chance of developing skin cancer increases as you age, likely because of the cumulative effect of years of UV exposure on the skin. By age 40, you have only accumulated 47 percent of the sun exposure you will get in your lifetime, assuming an average life span of 78 years.
Some research also attributes this trend to better skin cancer detection and more awareness of skin issues.
More than 55 percent of new melanoma cases are diagnosed in people ages 65 and older — and there are higher death rates among that age group, compared with younger people, as well.
4. Chemical Exposure
Exposure to certain chemicals can increase your risk of developing skin cancer.
Long-term exposure to large amounts of arsenic, a naturally occurring toxin, is associated with an increased risk of basal and squamous cell skin cancer. It’s often found in well water, but it can turn up everywhere from pesticides to tobacco smoke to brown rice.
Although arsenic can irritate the skin, the most harmful effects come from prolonged exposure to it from contaminated drinking water.
Being in contact with coal tar, paraffin, and certain types of petroleum also may put you at higher risk of developing skin cancer.
These may be present in industrial products or pesticides, says Howard Sobel, MD, a clinical attending cosmetic dermatologic surgeon at Lenox Hill Hospital in New York City.
5. Medications and Treatment
If you have had an organ transplant, you may have as much as a 100-times-greater risk of developing skin cancer than those who have not. This is due to the use of immunosuppressive medications to help your body accept the new organ. They help to mute the immune system, which may make it easier for cancerous tumors to grow.
Immunosuppressants are also used to fight 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 undergoing radiation treatment for cancer or UV light therapy can also be at higher risk of developing skin cancer and other cancers.
Radiation therapy, however, is also used to fight basal cell and squamous cell carcinoma. If skin cancer recurs at a spot in which radiation is applied, it typically is not used as a treatment again.
Research has found that people receiving high doses of UV light therapy, or psoralen plus ultraviolet A (PUVA), to treat the skin condition psoriasis over a long period of time may have a greater 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 UV light at a smaller range.
6. Past Skin Cancer
Having had a basal cell carcinoma, squamous cell carcinoma, or melanoma increases the risk of developing these or other skin cancers again.
In fact, as many as 43 percent of people who have had a skin cancer will see it recur, 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 may affect the basal cells one time and squamous cells another.
- Treatment or surgery did not remove all cancerous cells.
- Increased vigilance in detection, especially if you are following 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 occurring again. Regularly checking your skin and getting regular screenings with healthcare providers is also important.
7. Other Skin Problems
Having other issues with your skin, 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 issues can promote abnormal cell growth that eventually becomes cancer.
Moles on your skin also increase your 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 — also may increase skin cancer risks. This is especially true among people with severe cases as opposed to mild psoriasis, because of the greater inflammation involved.
8. Inherited Conditions
“Those with a family history of skin cancer have a greater risk [of developing skin cancer],” Dr. Sobel says.
Inheriting a condition known as basal cell nevus syndrome, for instance, means you are likely to develop numerous basal cell cancers, sometimes beginning in childhood or adolescence.
Other genetic skin conditions that increase the risk of basal and squamous cell skin cancers include:
- Fanconi anemia
- Epidermolysis bullosa
- Rothmund-Thomson syndrome
- Werner syndrome
- Bloom syndrome
- Muir-Torre syndrome
As for melanoma, genetic inheritance may account for 5 to 10 percent of all cases, with certain genetic mutations potentially increasing the risk even more for women. Not enough research exists to determine exactly how much genetic conditions increase your risk, however.
It’s also possible to inherit xeroderma pigmentosum, an uncommon condition that leaves skin unable to adequately repair DNA damage from UV exposure. This can also lead to melanoma, especially at a young age.
9. Viruses
A number of viruses are linked to increased skin cancer risk, often by weakening the immune system.
HIV, the virus that causes AIDS, can lead to basal cell and squamous cell cancers.
Some types of human papillomavirus (HPV), especially those affecting the genitals or anus or the skin around the fingernails, may lead to skin cancers in those areas.
HPV is spread 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 to arise from HPV’s presence.
“HPV is linked to squamous cell skin cancer, just as it is to cervical cancer,” Dr. Mark says. “If you see a visible wart, have it removed or frozen or treated topically. If it does not go away, it needs to be biopsied.”
Sobel says that other viruses related to elevated skin cancer risk include:
- Merkel cell polyomavirus
- Kaposi sarcoma-associated herpesvirus
- Human T-cell lymphotropic virus type 1
- Epstein-Barr virus
10. Smoking
Cigarette smoking is considered a risk factor for squamous cell carcinoma, particularly on the lips. It is not a known risk factor for basal cell carcinoma or melanoma.
Ingesting tobacco and smoke causes you to consume a number of carcinogens. These chemicals can damage cellular DNA and lead to 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 have a much higher risk, compared with people with naturally darker skin tones. This is because of the protective qualities of melanin, the natural pigment that gives skin a darker color.
The risk of skin cancer also is higher for people who:
- Freckle or burn easily
- Have natural blond or red hair
- Have green or blue eyes
This does not mean that people with darker skin tones cannot get skin cancer. In fact, on darker skin, it has a higher probability of appearing on skin that is not exposed to the sun. Survival rates for melanoma also are lower in people with darker skin tones than those with lighter ones.
12. Using a Tanning Bed
Although some people use a tanning bed instead of getting a tan by sunlight, tanning beds can greatly increase your 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 or younger who use a tanning bed also increase their risk of melanoma by 47 percent. Numerous states have banned young people from accessing tanning beds.
Tanning beds provide exposure to UV rays in concentrated and damaging doses. They damage skin cells just like the sun does, but often in more intense bursts.