"The sun shines bright on my Old Kentucky Home..." Maybe you know the line to that song or not. No matter.

Thing is - the sun shines bright these days anywhere you are on the planet, all year round, in cloud cover or snow cover.

When you're outside doing whatever - walking, swimming, playing volleyball or lying on a towel somewhere "catching some rays" - you're getting beamed with the sun's radiation.

That's why we all have to be smart about how we behave in and with the sun. Regardless of our age. Whatever color our skin is. Because the sun is relentless and you need to respect its power.

Why? Because skin cancer is the single most common malignancy in the United States, affecting millions of Americans every year.

Let's shine some sunlight on skin cancer.

Skin cancer basics

Skin cancer results when skin cells grow crazy. There are three major kinds of skin cancer - basal cell carcinoma, squamous cell carcinoma and melanoma.

Basal and squamous cell cancers usually show up in areas that the sun reaches, including your scalp, face, chest, arms and legs.

Those are the broad brush areas. Skin cancer also kisses the lips, ears, neck and hands. And that's not all.

You can also develop skin cancer where the sun don't shine - that is, beneath your fingernails, on your palms, between your toes and in the genital area.

Melanoma is the worst skin cancer because it can spread and latch onto other areas of the body. The big M can appear anywhere on the body.

Skin cancer demographics

This disease does not discriminate. It can and does affect all people - regardless of skin color.

It used to be that older people were most prone to this widespread cancer. Not any more. Youngsters in their teens and young adults are the fastest growing age groups developing skin cancers, in large part because of indoor tanning booths.

The American Cancer Society estimates there will be 81,240 new cases of melanoma and other types of skin cancer diagnosed.

These figures don't even begin to tell the whole story, though, because they don't include cases of basal and squamous cell skin cancers. When you add thosein, you're looking at millions of people being diagnosed with or having lived with some type of skin cancer.

According to the Skin Cancer Foundation -

• More than 3.5 million cases of skin cancer are diagnosed in two million people every year.
• That means skin cancers outpace the most common malignancies by a mile, accounting for more new cases than all breast, prostate, lung and colon cancers combined.

Here's a summary from the Mayo Clinic on what the different cancers look like:

Basal cell carcinoma

This cancer develops in areas that have been exposed to the sun - face, scalp and ears. It can appear as:

• A bump that's whitish or waxy
• Flat place that may be flesh colored or brown and looks like a scar

Squamous cell carcinoma

Also seen on sun-exposed areas, these cancers look like:

• A red, firm to the touch nodule or bump
• Scaly, crusted flat lesion

Melanoma

The worst form of skin cancer can be anywhere on the body. It most often appears in men on the head or neck or trunk, and in women on the lower legs. In people who have darker skin, melanoma often occurs in areas that aren't exposed to the sun - soles of feet, palms, between toes or fingers, or under nails.

Signs of melanoma can include any of the following:

• A large brown spot that has darker speckles
• A mole that bleeds, changes size, shape or color
• Small spot that has an jagged or irregular border with areas that tend toward red, white, blue or blue-black
• Dark spots or lesions on the fingertips or toes, palms or soles
• In mucous membranes around the mouth, nose, vagina or anus

Skin cancer causes and risk factors

The ultraviolet rays of sunlight are the major cause of skin cancers in areas of the body that are exposed to the sun.

Why the disease develops in areas that aren't in the sun, is not clear. It could also be that exposure to toxins in the environment may increase a person's risk of skin cancer. Conditions that weaken the immune system might also play a role.

Skin cancer is more common among individuals who have:

• Fair skin (blond, red hair and light-colored eyes)
• Lots of past sun burns
• Tons of time in the sun
• Lived in sunny or high-altitude areas
• Many moles
• Unusual spots known as actinic keratoses - rough, scaly patches that are dark pink to brown
• Family or personal history of skin cancer
• Weak immune system
• Increasing age