Melanoma is the deadliest type of skin cancer. It may begin in or near a mole that changes in color, shape, or size. Melanoma can occur anywhere on the body, but it's most common on areas exposed to the sun. Nonmelanoma skin cancers include basal cell and squamous cell skin cancers.

What is basal cell skin cancer?

The most common type of skin cancer, basal cell cancer, typically appears on skin that's had a lot of sun exposure, such as the face and neck. Your chances of getting basal cell skin cancer increase with age, but it's becoming more common in younger people.

Basal cell skin cancer develops in the lowest layer of skin and grows slowly. Because this type of cancer almost never spreads to other parts of the body, it's rarely fatal. But if it's not treated, it can eat away at surrounding skin and bone.

At first, basal cell skin cancer may look like a flat, shiny, yellowish or gray spot of skin. Or it may be a small, waxy-looking bump with rolled, pearly edges. Tiny blood vessels may appear at the edges, and the bump may bleed easily. As the cancer grows, it may develop a pit in the middle and become crusty. It can be various colors and usually doesn't hurt.

How does squamous cell skin cancer compare?

Because it's more likely to spread than basal cell skin cancer, squamous cell skin cancer can be more serious. It usually develops on the outer layer of sun-exposed skin. If squamous cell cancer spreads deeper into the skin, it can travel to other areas of the body.

Squamous cell skin cancer may look like a rough, thick, scaly lump, or it may be flat. It usually doesn't hurt, but it may bleed easily. Because different cancer types can look similar in the early stages, your healthcare provider will need to take a small sample to be examined more closely in a lab.

Am I at risk for skin cancer?

You're at higher risk for basal or squamous cell skin cancer if you're fair-skinned, male, have had skin cancer in the past, smoke, or have had radiation therapy for cancer. Other risk factors include exposure to chemicals such as arsenic, industrial tar, or paraffin; having had ultraviolet light treatment for psoriasis; having been overexposed to ultraviolet radiation from sunlight or tanning lights; or having human papillomavirus infection or a poor immune system.

How are skin cancers treated?

Most basal cell and squamous cell skin cancers can be removed with surgery. Whether you need other treatments depends on the cancer's location, cell type, and depth, and whether it's spread to other parts of the body.

How can I protect myself from skin cancer?

Even after your skin cancer has been removed, it can come back. To protect yourself:

* Avoid any unnecessary exposure to sun, especially between 10 a.m. and 4 p.m.

* Whenever you go outdoors, protect your skin with long-sleeved clothes and wide-brimmed hats. Choose a sunscreen with an SPF of at least 30 and protection against ultraviolet A (UVA) and ultraviolet B (UVB) rays.

* Protect your skin even on cloudy days; clouds don't block out ultraviolet rays.

* Reapply water-resistant sunscreen after swimming or sweating profusely, or every 2 to 3 hours.

* Wear wraparound sunglasses with lenses that filter out both UVA and UVB rays.

* Stay away from tanning booths and sun lamps.