Skin cancer: What you need to know

Skin cancer risk factors

The best way to lower your risk for skin cancer is to protect your skin from UV light. Use sunscreen on exposed skin whenever outside, and wear sun-protective clothing, including wraparound sunglasses, long sleeves, and a wide-brim hat.

Besides overexposure to UV rays, other factors that increase one’s risk for skin cancer include having

• fair skin or freckles
• blonde or red hair
• blue, green, or hazel eyes
• skin that burns easily
• a family history of skin cancer
• a tendency to develop many moles or abnormal-appearing or larger moles (larger than a rubber pencil top — approximately 6 mm)
• previous bad sunburns, especially sunburns that blister
• tanning bed use
• tobacco smoking
• medications or medical conditions that lower your immune system
• older age.

In addition to knowing your risk factors, it is important to understand the different types of skin cancer and the symptoms to watch for.

Types and symptoms of skin cancer

Most skin cancers start in the top layer of the skin, called the epidermis. The main difference between skin cancers is the type of cell from which each originates.

Because early recognition can make treatment easier and more effective, you should pay attention to changes in your skin. Overall, you should contact your doctor or dermatologist if you notice any suspicious spots, growths, or moles that get larger, change color, or change shape.

The two most common skin cancers are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) — sometimes called keratinocyte carcinomas. They are slow-growing and seldom spread to other parts of the body, especially if identified early. Both can be treated, but they can be disfiguring if left untreated. Less common but more dangerous is melanoma, which is responsible for the majority of skin cancer deaths. The even more rare Merkel cell carcinoma is an aggressive skin cancer that can spread quickly to other parts of the body.

The following sections describe these four skin cancers and their typical warning signs.

Basal cell carcinoma

Basal cell carcinoma (BCC) is the most common type of skin cancer, accounting for approximately 80% of cases. It starts in basal cells located deep in the epidermis. BCCs tend to grow slowly, and it’s rare for a BCC to spread to other parts of the body. But if left untreated, BCCs can grow into nearby areas, deep into the skin, and destroy bone and tissue. If not fully eradicated during treatment, BCCs can return to the same place. People with BCCs are also more likely to get new ones elsewhere.

BCCs usually appear as tiny, painless bumps with a pink, pearly surface. As it slowly grows, the center of the bump may become sore and develop into a crater that bleeds, crusts, or forms a scab. Although it is commonly located on the face, basal cell cancer can develop on the ears, back, and neck.

Squamous cell carcinoma

About 20% of skin cancers are squamous cell carcinoma (SCC). They begin in the squamous cells in the middle and outer parts of the epidermis. SCCs also are slow-growing, although they are more likely than BCCs to grow into deeper layers of the skin and spread to other parts of the body.

SCCs can appear as a small, red, painless lump or a dry skin patch that slowly grows and may develop into a non-healing sore. It usually occurs on the head, ears, and hands. SCCs sometimes develop from a precancerous skin growth called an actinic keratosis, a thin, rough, scaly patch on the skin that usually affects older adults after years of sun exposure. Actinic keratosis can also be very small, just a few millimeters in size.

Although BCC and SCC are the most common types, melanoma is less common and more dangerous because it can spread quickly.

Melanoma

Melanoma skin cancer is so named because it forms from melanocytes, the skin pigment-generating cells in the bottom layer of the epidermis. Melanoma only makes up about 1% of skin cancers, but it’s the deadliest because affected melanocytes can multiply and spread quickly.

Melanoma most commonly develops on the back, chest, and legs, but it can appear anywhere on the body. Most of the time melanoma develops on normal-looking skin, but it can grow out of an existing mole. Identifying melanoma can be challenging, as it can appear be a single dark skin spot or vary in shape, size, or color. Following the ABCDE guideline is a good way to recognize melanoma symptoms or potential warning signs.

A: Asymmetry. One half of a mole or spot does not match the other.

B: Border irregularity. The edges are ragged, notched, or blurred.

C: Color. The pigmentation is not uniform; the coloring may include shades of tan, brown, or black; dashes of red, white, or blue can add to the mottled appearance.

D: Diameter. A mole or spot is greater than 1/4 inch in diameter, or about the width of a pencil eraser. However, melanomas can be smaller.

E: Evolving. A mole or spot looks different from others and/or changes size, shape, or color; or begins to itch, hurt, or bleed. A mole that bleeds, feels numb, or has a crusty surface also may indicate a melanoma.

Merkel cell carcinoma

Another rare but aggressive type of skin cancer is Merkel cell carcinoma. This skin cancer forms from Merkel cells, which are tiny, oval-shaped cells found in the layer of basal cells. It is exceptionally uncommon; Merkel cell carcinoma is 40 times rarer than melanoma and usually develops in areas that receive a lot of sun exposure, such as the face, neck, and backs of the hands.

Merkel cell cancer can appear as a painless reddish or purplish bump on the skin that often grows rapidly. In addition to sun exposure, other risk factors include an immune system weakened by disease or a virus called Merkel cell polyomavirus (MCV). Overall risk also increases with age.

How is skin cancer treated?

Many skin cancers are treatable if caught early. Your dermatologist may recommend various treatments depending on the type of skin cancer, its size and location, how far it has spread, and whether a treated skin cancer has returned. Because skin cancers can differ in their behavior, treatment depends on the type of cancer and how early it is found.

Basal cell carcinoma and squamous cell carcinoma. For the two most common types, basal cell carcinoma and squamous cell carcinoma, treatment options are often similar. These include:

• cutting out the cancer and a small amount of healthy tissue around it (a procedure called excision)
• scraping away the cancer with a surgical loop, then using an electric probe to destroy any remaining cancer cells (this is known as electrodessication and curettage)
• freezing cancer cells with liquid nitrogen (called cryotherapy)
• destroying the tumor with radiation
• Mohs surgery, a specialized type of surgery where the cancer cells are cut out in stages with a very narrow amount of normal skin and then immediately examined under the microscope to identify any areas of remaining cancer. A skin graft may be necessary if a large are of skin is removed.
• applying drugs directly to the skin or injecting them into the tumor
• using a narrow laser beam to destroy the cancer.

Melanoma. Surgery is the initial treatment for melanoma that appears in just one spot. The doctor removes the visible tumor, along with 0.5 to 2 centimeters of healthy skin around the tumor, depending on the depth of the melanoma in the skin.

If the melanoma is more than 0.7 millimeters deep, your doctor will discuss if additional evaluation is needed to determine if melanoma has spread to nearby lymph nodes, by either biopsy or sampling of the lymph nodes, or imaging such as ultrasound.

Additional therapies can often help people with thicker tumors that have grown deep into the skin, spread to other areas of the body, or both. Most often, patients are treated with immunotherapy and/or drugs designed to block major pathways that allow cancers to grow. Radiation therapy and chemotherapy are less effective, but can be used when other treatments stop working.

Merkel cell carcinoma. Treatment depends on the location and size and if it is contained to the area. Doctors may check nearby lymph nodes and use imaging scans to determine if it has spread to other parts of the body. If not, then surgery usually involves removing the cancer along with a small amount of healthy skin around it. If it has spread, treatment may include radiation, chemotherapy, immunotherapy, or a combination of these approaches.

Skin cancer prevention

Prevention and regular monitoring can help lower the risk of developing skin cancer or allow for early detection by catching it early. The best way to lower your risk for skin cancer is to protect your skin from UV light. Avoid the sun from 10 a.m. to 2 p.m., when ultraviolet (UV) radiation exposure is at its peak, and avoid tanning beds.

To help protect yourself against and lower the chances of developing skin cancer, follow standard sun protection guidelines such as using sunscreen, wearing sun protective clothing and accessories, and regularly checking your skin.

Apply sunscreen

The mantra for sunscreen is to use it early and often. Apply sunscreen 15 to 20 minutes before heading outside, then reapply every two hours. Use at least two tablespoons to cover exposed areas of the face and body, with a nickel-sized dollop to the face alone. And don’t forget the ears, the tops of the feet, and the backs of the legs.

There are two basic types of sunscreen: chemical or mineral. Chemical sunscreens absorb the sun's rays through a chemical reaction in the skin, and mineral sunscreens, such as zinc oxide and titanium dioxide, physically block UV radiation from touching the skin. When choosing a sunscreen, focus on broad-spectrum coverage, SPF number, and water resistance.

Broad-spectrum coverage (or multi-spectrum or UVA/UVB protection). This type of sunscreen protects against both UVA and UVB sun rays. Both these types of UV rays can damage DNA, raising the risk of skin cancer. UVA rays are the leading cause of sunburns, while UVBs penetrate deeper into the skin and contribute more to skin aging and wrinkles.

SPF. You are most likely familiar with the acronym SPF, which stands for sun protection factor. The higher the SPF number, the greater the protection. For instance, SPF 30 blocks 97% of the UVB rays, and SPF 50 blocks 98%. Anything higher than SPF 70 does not provide much extra protection compared to SPF 30, but this only works if you do not underapply or use too thin a layer. Stick with sunscreen stick, lotion, or spray with at least SPF 30 to 50.

Water resistance. No sunscreen is waterproof, but water-resistant sunscreen withstands water and sweat for a limited time, usually between 40 to 80 minutes. It’s best to reapply sunscreen every two hours when outdoors, and after getting out of the water or if you’ve been sweating a lot.

Use sun-protective accessories and clothing

Wear a hat with at least a four-inch brim all around and sunglasses that block sunlight from the sides. As for clothing, opt for synthetic fibers such as polyester, Lycra, nylon, and acrylic. These have elastic threads that pull the fibers close together, which reduces the spaces between them and thus blocks more of the sun’s UV rays. Color matters, too. Darker colors are better at protecting the skin against UV rays than lighter colors.

Some clothing brands offer specially designed sun-protection clothing, which is marked with a UPF (ultraviolet protection factor) label and number. The number indicates what fraction of the sun’s UV rays can penetrate the fabric and reach your skin. For example, a shirt with a UPF of 50 fabric blocks 98 percent of the sun’s rays.

Get and perform skin checks

Unlike some other cancer screenings, there isn’t a standard schedule for when or how often professional skin cancer checks should occur for people without symptoms. Ask your doctor or dermatologist what’s right for you, especially if you’re at higher risk for skin cancer. For example, if you recently had skin cancer, it is important to get checks more frequently in the two years after your diagnosis. People with a first-degree relative who is diagnosed with melanoma should also get regular skin cancer screenings.

Regardless of risk factors, make a point to routinely perform your own skin self-exam. Check your head, face, and body in the mirror to look for unusual spots, growths, or suspicious moles. Ask your spouse, partner, or a family member to look at your back and other areas you can’t see, like the scalp and the backs of the thighs and ears. Be sure to consult your doctor or dermatologist if you notice any suspicious spots, growths, or moles that get larger, become darker, or change shape.