What Are Skin Cancer Risk Factors?

Pharmacists have a role to play in helping patients prevent and seek treatment for skin cancer, which is an uncontrolled overgrowth of abnormal skin cells. This occurs when the DNA of skin cells are damaged and remain unrepaired, triggering mutations that cause skin cells to multiply and form tumors.¹

Skin cancer is the most common form of cancer in the United States,² with more cases diagnosed each year than all other cancers combined. In fact, about 20% of the US population will develop the disease by age 70.³ Skin cancer is prevalent across the United States (see the figure⁴ for state-specific statistics), and the annual cost of treatment nationwide is estimated at $8.1 billion.

COMMON SKIN CANCERS

Several types of skin cancer exist, but the 3 most common are basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma. BCC and SCC are nonmelanoma cancers.

BCC is the most common form of skin cancer, with new diagnoses affecting more than 4 million Americans annually.⁵ This type forms in the basal cells, lining the deepest level of the epidermis.⁵ Basal cells are responsible for the production of new skin cells.

The lesions of BCC often look like open sores, red or pink patches, scars, or shiny bumps. Although BCCs rarely metastasize, pharmacists and patients should not take them lightly, as they can cause disfigurement if not promptly treated.⁵

The vast majority of BCCs are caused by a combination of intense and long-term exposure to the sun’s UV rays and are typically found on parts of the body that are exposed to the sun, especially the back, ears, face, neck, scalp, and shoulders. Tumors can develop on unexposed areas because of factors other than the sun, though these malignancies are rare. These factors include arsenic contact; chronic inflammatory skin conditions; complications of burns, infections, scars, or tattoos; radiation exposure; and unhealed open sores.⁵

Consistent sun exposure over time and intense exposure resulting in sunburn together damage the skin and increase the risk of BCC. Other factors that increase the risk are blond or red hair; blue, green, or gray eyes; and fair skin.⁶ Risk can also be hereditary. BCC is most often found in older adults, but over the past few decades, the average age has steadily declined. Dermatologists report an increase in BCC diagnoses in people in their 20s and 30s.⁶

SCC is the second-most-common form of skin cancer, with new diagnoses affecting about 1 million Americans annually.⁷ More than 15,000 Americans die each year from SCC. Squamous cells are found just below the outer surface of the skin, acting as the skin’s inner lining and providing a thin membrane that allows small molecules to pass into the body. The lesions of SCC appear as elevated growths, open sores, scaly red patches, or warts.⁷ These lesions may bleed or crust.⁸ SCC may become disfiguring or lead to death if left untreated.⁷

Cumulative, long-term sun exposure over a lifetime causes most SCCs. This includes daily, year-round exposure; intense exposure during warm months; and exposure during vacation in sunny areas.⁷ In addition, the use of indoor tanning beds is increasing the number of cases in young women.⁷ Most SCCs occur in sun-exposed areas of the skin. However, all areas of the body are susceptible to SCCs, including the genitals and mucous membranes.

Men are at least twice as likely to develop SCC as women, and SCC is the most common type of skin cancer in African Americans.⁸ African Americans typically develop the disease at the site of burn injuries or preexisting inflammatory skin conditions.⁸ Although lighter-skinned individuals have a higher likelihood of developing skin cancer, SCC diagnoses in darker-skinned people, such as Latinos, have increased sharply.⁸

The risk factors for developing SCC are the same as those for BCC, with several noteworthy exceptions. Any use of tanning beds increases the risk of developing SCC by 67%.⁸ Also, anyone who has previously had BCC is at higher risk for developing SCC.⁸ People living with xeroderma pigmentosum, a hypersensitivity to UV rays, and those with reduced immune system function are also at higher risk for developing SCC.⁸

Finally, melanoma is the most dangerous form of skin cancer. Melanomas originate in melanocytes, pigment-producing cells in the epidermis. Melanomas often develop from moles. About 180,000 Americans receive a melanoma diagnosis every year; of these, nearly 10,000 will die from the disease each year, with men being the majority.⁹

Melanomas are usually black or brown but can be blue, pink, purple, red, skin colored, or white.⁹ The acronym ABCDE is helpful for differentiating a melanoma from a normal mole: asymmetrical, border (uneven), color (various), diameter (larger), and evolving (changing).⁹ Melanomas fall into 4 basic types. Superficial spreading melanoma (SSM) is the most common, comprising about 70% of all cases.¹⁰ It is most often seen in young people and grows along the top layer of the skin. At first, SSM appears as a flat or slightly raised patch that is asymmetrical and discolored with irregular borders. Over time, the growth may penetrate more deeply. SSM is most likely to occur on the trunk in men, the legs in women, and the upper back in both.¹⁰

Lentigo maligna is similar to SSM in appearance but is most often found on sun-exposed skin of elderly individuals. Common sites are the arms, the ears, the face, and the upper torso. Lentigo maligna is the most common type of melanoma in Hawaii.¹⁰

Acral lentiginous melanoma also spreads topically before moving deeper into the skin. It usually presents as a black or brown discoloration under the nails, on the soles of the feet, or on the palms of the hands. This is the most common melanoma in African Americans and Asian Americans and the least common among Caucasians.¹⁰

Nodular melanoma is usually already invasive by the time of diagnosis. It presents as a bump that is usually black but can be any color and is found on the arms, legs, and torsos of elderly individuals as well as on the scalp in men. Nodular melanoma is the most aggressive form and accounts for about 10% to 15% of cases.¹⁰

Risk factors for melanoma include male sex, fair skin, family or personal history of melanoma, freckling, light hair, moles, older age, xeroderma pigmentosum, and a weakened immune system.¹¹

SKIN CANCER PREVENTION

Skin cancers are most often curable, but early detection and prompt treatment are imperative, and pharmacists can help patients with prevention and advise them to seek treatment from a doctor when necessary. Sun safety habits are core to prevention of all skin cancers. These habits include avoiding sunburns, tans, and UV tanning beds; dressing to cover the skin; seeing a dermatologist for an annual skin exam; seeking shade between 10 am and 4 pm; self-examining the skin every month; and using broad-spectrum sunscreen with sun protection factor 15 or higher applied to the body 30 minutes prior to exposure and reapplied every 2 hours.¹²

Kathleen Kenny, PharmD, RPh, has more than 25 years of experience as a community pharmacist and is a freelance clinical medical writer based in Colorado Springs, Colorado.

References

• Skin cancer information. Skin Cancer Foundation website. skincancer.org/skin-cancer-information. Accessed March 5, 2019.
• CDC. What is skin cancer? cdc.gov/cancer/skin/basic_info/what-is-skin-cancer.htm. Updated April 23, 2018. Accessed March 5, 2019.
• Skin cancer facts and statistics. Skin Cancer Foundation website. skincancer.org/skin-cancer-information/skin-cancer-facts. Updated February 25, 2019. Accessed March 5, 2019.
• CDC. Leading cancer cases and deaths, male and female, 2015. gis.cdc.gov/Cancer/USCS/DataViz.html. Accessed March 5, 2019.
• Basal cell carcinoma (BCC). Skin Cancer Foundation website. skincancer.org/skin-cancer-information/basal-cell-carcinoma. Accessed March 5, 2019.
• Basal cell carcinoma - causes and risk factors. Skin Cancer Foundation website. skincancer.org/skin-cancer-information/basal-cell-carcinoma/bcc-causes-and-risk-factors. Accessed March 5, 2019.
• Basal cell carcinoma prevention guidelines. Skin Cancer Foundation website. skincancer.org/skin-cancer-information/basal-cell-carcinoma/bcc-prevention-guidelines. Accessed March 5, 2019.
• Squamous cell carcinoma (SCC). Skin Cancer Foundation website. skincancer.org/skin-cancer-information/squamous-cell-carcinoma. Accessed March 5, 2019.
• Squamous cell carcinoma - causes and risk factors. Skin Cancer Foundation website. skincancer.org/skin-cancer-information/squamous-cell-carcinoma/scc-causes-and-risk-factors. Accessed March 5, 2019.
• Melanoma. Skin Cancer Foundation website. skincancer.org/skin-cancer-information/melanoma. Accessed March 5, 2019.
• Types of melanoma. Skin Cancer Foundation website. skincancer.org/skin-cancer-information/melanoma/types-of-melanoma. Accessed March 5, 2019.
• Mayo Clinic. Skin cancer. mayoclinic.org/diseases-conditions/skin-cancer/symptoms-causes/syc-20377605. Published February 20, 2019. Accessed March 5, 2019.