Skin Cancer is the most common type of cancer in the United States.
Skin Cancer and Pre-Cancer
Skin cancer is the most common type of cancer in the United States – by the age of 70 years, 1 in 5 Americans will have developed some form of skin cancer. Among the largest contributors to this statistic is excessive sun exposure. In fact, having five or more sunburns doubles the risk of melanoma, a particularly aggressive type of skin cancer. More than 9,500 people are diagnosed with skin cancer every day, and more than 2 people die every hour from skin cancer in the U.S. Early detection is key to give the greatest chance at successful treatment as the 5-year survival rate for melanoma is 99% when it is detected in the earliest stages.
Please continue reading to learn more about skin cancer and precancerous skin lesions. If you have skin cancer, it is important to know what type it is because this affects your treatment and prognosis.
What is skin cancer?
Skin cancer is an abnormal, uncontrolled growth of skin cells. It usually develops in areas of the skin that are exposed to UV radiation in sunlight (scalp, face, ears, neck, chest, arms, hands), but it can also occur in areas that are not usually exposed to the sun (below the nails, on the palms and soles, and in the genital area). There are three main types of skin cancer, basal cell cancers, squamous cell cancers, and melanoma.
Basal cell carcinoma
A basal cell cancer appears as a waxy or pearly bump or a flat flesh-colored or brown lesion. Sometimes a basal cell carcinoma can be a scabbing and bleeding sore that appears and disappears over time.
Basal cell carcinomas are the most common type of skin cancer – making up roughly 8 out of 10 skin cancers. The cancerous growth starts in the basal cells, which are present in the lower epidermis.
Basal cell cancers typically develop in sun-exposed areas, are slow-growing, and rarely spread to other areas of the body. However, if left untreated, they can invade the bone and other tissues under the skin.
Squamous cell carcinoma
A squamous cell cancer can appear as a firm, red nodule or a flat lesion with a crusted, scaly surface. This type of cancer frequently develops in sun-exposed areas like the ears, face, and hands. In people with darker skin tones, squamous cell cancers can appear in areas that are not typically exposed to sunlight. Sometimes, squamous cell carcinomas start as actinic keratoses, which are precancerous lesions (described below).
Around 2 out of 10 skin cancers are squamous cell carcinomas. The cancerous growth starts in the squamous cells that are present in the upper epidermis. Compared to basal cell carcinomas, squamous cell carcinomas have a higher likelihood of invading deeper into the skin and spreading to other areas of the body.
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Melanoma is a type of skin cancer that appears as a large brownish spot with darker colored speckling. It can also develop in an existing mole that changes in size, shape, color or in a mole that bleeds. Some melanomas are small lesions with irregular borders and blue, black, red, white, or pink portions. Others are painful lesions that itch and burn. Melanomas can develop in sun-exposed skin as well as the palms, soles, and mucous membranes that line the insides of the mouth, nose, anus, and vagina.
Melanoma develops from melanocytes, which are pigment-manufacturing cells in the epidermis. Although less common than basal cell and squamous cell skin cancers, melanomas are more likely to grow and spread if left untreated.
Precancerous skin lesions
Precancerous skin lesions, such as actinic keratoses, Bowen’s disease, and keratoacanthoma, appear on sun-exposed areas as a result of ultraviolet radiation. Doctors recommend treating precancerous lesions because 1) it is hard to tell them apart from true skin cancers, and 2) because they can transform into invasive skin cancers if left untreated.
One of the most common types of precancerous skin lesions is actinic keratoses or solar keratoses. They appear as small, rough, pink/flesh-colored, scaly spots that are usually less than 1/4 inch in size. Typical locations include the face, ears, hands, and arms. Middle-aged people with fair skin are at the greatest risk. Most people who have actinic keratoses will have more than one. These precancerous lesions tend to grow slowly and may not cause any symptoms, or they may be sore and itchy. They can occasionally go away on their own but may come back. Most actinic keratoses do not become cancer, but some can transform into squamous cell skin cancer.
Bowen’s disease or squamous cell carcinoma in situ is the earliest stage of squamous cell cancer (SCC) which has not yet invaded deeper skin layers. Keratoacanthomas are dome-shaped precancerous lesions that occur on sun-exposed skin. They tend to grow rapidly initially but then slow down and may even shrink and go away without treatment. However, because their growth is unpredictable and they can be hard to tell apart from squamous cell cancers, experts recommend treating keratoacanthomas.
Less common types of skin cancer
Some other types of skin cancer, such as Merkel cell carcinoma, cutaneous lymphoma, Kaposi sarcoma, and adnexal skin tumors, are rare and account for less than 1% of all skin cancers. They are treated differently than the three common types of skin cancer.
Diagnosis and treatment of skin cancers
A trained dermatology medical provider can diagnose skin cancer by examining your skin or removing a small sample from a suspicious lesion for testing in the laboratory (this is called a skin biopsy). If skin cancer is detected, additional tests may be done to determine the extent of the cancer, such as imaging nearby lymph nodes to check for spread.
Treatment options for skin cancer include cryosurgery (destroying the cancer by freezing it with liquid nitrogen), excisional surgery (cutting out the cancerous tissue with a margin of healthy skin), Mohs surgery (layer-by-layer removal of the cancer to conserve as much healthy skin as possible), and curettage and electrodesiccation (scraping away cancer cells with a blade and applying an electric needle to destroy the remaining cancerous cells). Chemotherapy, radiation therapy, photodynamic therapy, and biological agents are other options for skin cancer treatment.
Skin cancer prevention
Skin cancers can be prevented with some lifestyle changes, such as avoiding sun exposure as much as possible, especially the mid-day sun, which is strongest between 10 am and 4 pm. Wearing year-round sunscreen plays a major role in protecting the skin (UV radiation is present even on cloudy days). Protective clothing such as broad-brimmed hats, long-sleeved tops, trousers, and dark and tightly woven clothing offers more protection than sunscreen does alone. Also, the tanning beds are avoidable because the light used here includes UV rays and increases the risk of skin cancer.
Last but not least, regular skin checks with a reputable dermatology clinic can help to detect skin cancer in the early stages or identify changes in existing moles, birthmarks, bumps, freckles, etc. A complete skin check includes the scalp, face, ears, neck, chest, back, trunk, underarms, arms, legs, feet, palms, and soles, the spaces between the fingers and toes, as well as the genital area and the skin between the buttocks.