by Dr. C.H. Weaver M.D. updated 7/2021
Skin cancer is the most common form of cancer in the United States, with more than 1 million new cases each year. Skin cancer is often divided into two broad categories: melanoma and non-melanoma. Non-melanoma skin cancer refers to several different types, but the most common are basal cell carcinoma and squamous cell carcinoma.1
Melanoma is less common than non-melanoma skin cancer, but it tends to be much more aggressive. Of the more than 1 million new diagnoses of skin cancer each year, roughly 62,000 involve melanoma. More than 8,000 people die of melanoma each year in the United States. What makes melanoma so dangerous is that it is more likely than other types of skin cancer to spread to other parts of the body (metastasize). Melanoma can occur anywhere on the body, and the first signs may be a mole that bleeds, changes appearance, or has an irregular shape or more than one color.1,2
Basal cell carcinoma accounts for roughly 80 percent of all cases of non-melanoma skin cancer.3 It most commonly develops on sun-exposed skin, with the head (particularly the nose) and the neck being the most common sites. Although the appearance of basal cell carcinoma varies, it often appears as a raised bump with a smooth, pearly appearance. It may also look like a firm, flat scar.4 Basal cell carcinoma very rarely metastasizes, but it can cause extensive local damage to the skin and the surrounding tissues.
Dr. Ken Lee, MD, director of dermatologic and Mohs surgery and associate professor of dermatology at Oregon Health & Science University, explains, “Although basal cell carcinoma is not a deadly cancer, it’s very destructive. If left unchecked, it will just continue to get larger and larger. And since it occurs in areas of sun exposure, a lot of these occur on the face. The larger they are, the more that needs to be removed and the bigger the reconstruction that is needed to repair them. It’s not an insignificant cancer because of where it occurs, and that’s on cosmetically sensitive areas.”
Squamous cell carcinoma accounts for roughly 20 percent of all cases of non-melanoma skin cancer5 and commonly involves the head or neck. The cancer may appear as a red bump or as a rough or scaly area on the skin.4 Squamous cell carcinoma is more likely than basal cell carcinoma to spread to lymph nodes and distant parts of the body.
An alarming trend in both melanoma and non-melanoma skin cancers is that the frequency of these cancers is increasing—including the frequency in children and young adults.6,7 “We are in the midst of a skin cancer epidemic,” says Dr. Lee. “The rate has been rising for all skin cancers. This probably reflects lifestyle changes over the past few decades.”
Risk Factors for Skin Cancer
Although no one is guaranteed protection from skin cancer, several characteristics or exposures increase the likelihood that you will develop it:
Personal and family history. As is the case for several types of cancer, a history of skin cancer in your family increases your risk of developing the disease.8
Hair/eye/skin color. Having blond or red hair, blue or green eyes, or light-colored skin makes you more susceptible to skin cancer.3,5 “A lot of people think that they are not fair skinned and tan easily,” says Dr. Lee, “but most Caucasians are fair skinned and burn easily.”
Moles. Having a greater number of moles increases your risk of skin cancer. Atypical moles—also known as dysplastic nevi—may carry a particularly high risk. Atypical moles look different from common moles; they may be larger or have an indistinct or irregular border.8,9
Actinic keratoses. Also known as solar keratoses because of their link with sun exposure, actinic keratoses are a type of precancerous change to the skin.2 They often appear as rough scaly patches on the skin or as a cracked and peeling area on the lower lip. Without treatment some actinic keratoses will develop into squamous cell carcinoma.
Sun exposure. Exposure to ultraviolet (UV) radiation increases the risk of both melanoma8 and non-melanoma skin cancer.3,5 The ultraviolet radiation from the sun that reaches the earth includes both ultraviolet B (UVB) and ultraviolet A (UVA). Exposure to UV radiation is greatest at latitudes closer to the equator, at high altitude, and when the sun in highest in the sky.
Tanning beds and sunlamps. These products also expose the skin to ultraviolet radiation and are believed to increase the risk of skin cancer.10
Immunosuppression. People who are immunosuppressed, such as those undergoing organ transplantation, have an increased risk of developing skin cancer.3,5,8
Prevention of Skin Cancer
Sun exposure contributes to both melanoma and non-melanoma skin cancer, and sun protection over the course of a lifetime is the most important aspect of skin cancer prevention. Because much of our sun exposure occurs during childhood, it is important for parents and grandparents to help children develop good sun protection habits.
According to Dr. Lee, sun protection involves more than just sunscreen. “Sunscreen is just one aspect of an overall sun protection program,” he stresses. Optimal sun protection involves avoidance of the sun during peak hours, use of protective clothing such as hats, and then sunscreen. “The problem,” explains Dr. Lee, “is that people negate the effect of the sunscreen because they don’t use common sense. They feel that sunscreen gives them carte blanche to stay out in the sun.”
Dr. Lee also points out that many people use sunscreen incorrectly, which reduces its effectiveness. “People put on only about 25 to 30 percent of the amount of lotion that is needed to actually get the SPF [sun protection factor] on the label. And then they don’t put it on evenly.” Reapplying sunscreen regularly is also important. “You need to reapply at least every two hours, if not every hour because you probably didn’t put enough on in the first place,” says Dr. Lee, who recommends using a sunscreen with an SPF of at least 30. Choosing a sunscreen that feels good on your skin may motivate you to put enough on and to reapply regularly.
Finally, Dr. Lee recommends choosing a broad-spectrum sunscreen that protects against UVA and UVB.
Early Detection of Skin Cancer
Because skin cancer affects people of all ages, it’s important that we all learn to recognize the signs. Dr. Lee, who treats many young people with skin cancer, points out that melanoma is the second most common cancer (after breast cancer) in women between the ages of 30 and 35 and the most common cancer in women between the ages of 25 and 29.
As a general rule, Dr. Lee recommends watching for “anything that’s changing, anything that’s bleeding or not healing, or anything new.” For melanoma specifically, using the “ABCDE guidelines” can help you recognize suspicious skin changes.11 A refers to asymmetry, B refers to border, C refers to color, D refers to diameter, and E refers to evolving. A skin lesion (typically a mole) may be a cause for concern if it is asymmetric (one half is different from the other half), has an irregular or jagged border, has more than one color, is larger in diameter than a pencil eraser, or is changing.
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Although these criteria can help you recognize melanoma, it’s important to remember that it’s possible for melanoma to not have any of these characteristics, and it’s also possible for a non-cancerous skin change to have all these characteristics.
In addition to monitoring your own skin, you may benefit from regular skin exams by a physician. “If you have a family history or personal history of skin cancer, you really need to be seen by a dermatologist once a year,” says Dr. Lee. If you don’t have a family or personal history of skin cancer but have other risk factors, you may want to see a dermatologist for a baseline skin exam.
Treatment of Skin Cancer
Surgery is the mainstay of treatment for non-melanoma skin cancer, and several different kinds of surgery are available. Depending on the type, extent, and location of non-melanoma skin cancer, it may be removed by electrodessication and curettage (a technique that involves scraping and burning the abnormal area), surgical excision (use of a scalpel to remove the cancer and some surrounding normal tissue), laser surgery, cryosurgery (freezing), or a technique known as Mohs micrographic surgery.
Mohs is complicated and requires expertise, but it is often recommended for the treatment of high-risk basal cell carcinoma or squamous cell carcinoma. In this procedure a doctor removes thin layers of skin one at a time and evaluates them for cancer while the patient waits. The doctor keeps removing layers of skin until he or she reaches a layer that is cancer-free. This procedure removes the least amount of normal tissue and also has the highest cure rates for both primary and recurrent cancers.12
Certain patients with non-melanoma skin cancer may be candidates for nonsurgical treatments, such as radiation therapy, topical therapy (application of medications to the skin), or photodynamic therapy. Photodynamic therapy involves the use of an agent that collects in cancer cells and makes them sensitive to light. Light is then applied to the area to destroy the cancer cells.
Surgery is also the primary treatment for melanoma, but melanoma patients—particularly those with more-advanced disease—may undergo additional procedures and treatments. These may include removal and evaluation of nearby lymph nodes, delivery of chemotherapy to the affected limb (isolated limb perfusion), whole-body (systemic) treatment with a chemotherapy or immunotherapy drug, and radiation therapy.13
For patients with melanoma that has spread to distant sites in the body, the available treatments have limited effectiveness and survival remains poor.1 The poor prognosis of metastatic melanoma highlights the importance of prevention and early detection. Patients with melanoma that has metastasized may wish to consider participating in clinical trials of new treatment approaches.
How to Do a Skin Self-exam
Your doctor or nurse may suggest that you do a regular self-exam to check for skin cancer, including melanoma.
The best time to do this exam is after a shower or bath. You should check your skin in a room with plenty of light. You should use a full-length mirror and a handheld mirror. It’s best to begin by learning where your birthmarks, moles, and other marks are and their usual look and feel.
Check for anything new:
- New mole that looks different from your other moles
- New red or darker-color flaky patch that may be a little raised
- New flesh-colored firm bump
- Change in the size, shape, color, or feel of a mole
- Sore that does not heal
Check yourself from head to toe. Don’t forget to check your back, scalp, genital area, and between your buttocks.
- Look at your face, neck, ears, and scalp. You may want to use a comb or a blow dryer to move your hair so that you can see better. You also may want to have a relative or friend check through your hair. It may be hard to check your scalp by yourself.
- Look at the front and the back of your body in the mirror, then raise your arms and look at your left and right sides.
- Bend your elbows. Look carefully at your fingernails, palms, forearms (including the undersides), and upper arms.
- Examine the back, front, and sides of your legs. Also look around your genital area and between your buttocks.
- Sit and closely examine your feet, including your toenails, your soles, and between your toes.
By checking your skin regularly, you will learn what is normal for you. It may be helpful to record the dates of your skin exams and to write notes about the way your skin looks. If your doctor has taken photos of your skin, you can compare your skin with the photos to help check for changes. If you find anything unusual, see your doctor.14
Links to More Information about Skin Cancer
Non - melanoma Skin Cancer Associated with Increased Risk of Other Cancers
Individuals who have been diagnosed with squamous cell or basal cell carcinoma have an increased risk of developing subsequent cancers other than skin cancer. These results were published in the Journal of the National Cancer Institute.14
Researchers affiliated with the Give Us a Clue to Cancer and Heart Disease (CLUE) study recently evaluated data to explore the potential relationship between non-melanoma skin cancers and the increased risk of subsequent cancers. The researchers compared 769 patients with a history of non-melanoma skin cancers with 18,405 patients without a history of non-melanoma skin cancers and evaluated the risk of subsequent new cancers in both groups.
- The risk of a subsequent cancer was increased nearly twofold among individuals who had been diagnosed with prior non-melanoma skin cancers compared with individuals who had not had a non-melanoma skin cancer diagnosis.
- This increased risk was noted for both squamous cell carcinoma and basal cell carcinoma.
- Patients who had been diagnosed with non-melanoma skin cancer at a younger age had a significantly increased risk of subsequent cancers compared with those who had been diagnosed at a later age.
The researchers concluded that there is a strong association between the diagnosis of non-melanoma skin cancer and the risk of a subsequent new cancer, particularly among younger patients.
- Cancer Facts and Figures 2019. American Cancer Society Web site. Available at http://www.cancer.org/docroot/STT/stt_0.asp. Accessed December 29, 2019.
- Melanoma Treatment (PDQ®). National Cancer Institute Web site. Available at: http://www.cancer.gov/cancertopics/pdq/treatment/melanoma/patient. Accessed December 29, 2019.
- Rubin AI, Chen EH, Ratner D. Basal-cell carcinoma. New England *Journal of Medicine.*2005;353(21):2262-69.
- Skin Cancer Treatment (PDQ®). National Cancer Institute Web site. Available at: http://www.cancer.gov/cancertopics/pdq/treatment/skin/patient. Accessed December 29, 2018.
- Alam M, Ratner D. Cutaneous squamous-cell carcinoma. New England *Journal of Medicine.*2001;344(13):975-83.
- Christenson LJ, Borrowman TA, Vachon CM, et al. Incidence of basal cell and squamous cell carcinomas in a population younger than 40 years. *Journal of the American Medical Association.*2005;294(6):681-90.
- Strouse JJ, Fears TR, Tucker MA, Wayne AS. Pediatric melanoma: Risk factor and survival analysis of the Surveillance, Epidemiology and End Results Database. Journal of Clinical Oncology. 2005;23(21):4735-41.
- Miller AJ, Mihm MC Jr. Melanoma. New EnglandJournal of Medicine. 2006;355(1):51-65.
- What You Need to Know About™ Moles and Dysplastic Nevi (NIH Publication 99-3133). National Cancer Institute Web site. Available at: http://www.cancer.gov/cancertopics/wyntk/moles-and-dysplastic-nevi. Accessed December 29, 2019.
- Sunbeds, Tanning, and UV Exposure (Fact Sheet No. 287). World Health Organization Web site. Available at http://www.who.int/mediacentre/factsheets/fs287/en/print.html.
- Abbasi NR, Shaw HM, Rigel DS, et al. Early diagnosis of cutaneous melanoma: Revisiting the ABCD criteria. Journal of the American Medical Association. 2004;292(22):2771-76.
- Skin Cancer Treatment (PDQ®). National Cancer Institute Web site. Available at: http://www.cancer.gov/cancertopics/pdq/treatment/skin/HealthProfessional. Accessed December 29, 2019.
- Melanoma: Treatment Guidelines for Patients, version III/September 2005. National Comprehensive Cancer Network Web site. Available at: http://www.nccn.org/patients/patient_gls/_english/_melanoma/contents.asp. Accessed December 13, 2019.
- Chen J, Ruczinski I, Jorgensen TJ, et al. Nonmelanoma skin cancer and risk for subsequent malignancy. Journal of the National Cancer Institute. 2008;100(17): 1215-22.