Each year, skin cancer affects more Americans than breast, prostate, lung, and colon cancers combined. More than 3 million people will learn they have nonmelanoma skin cancer, and nearly 90,000 will find out they have melanoma. About 1 out of every 5 people will develop skin cancer at some point in their lifetime.

Early detection and treatment is key to beating skin cancer. This is especially true of melanoma, which is the deadliest form of skin cancer.

Skin cancer starts as moles or other growths on your skin that change over time. One way to spot these growths early is to get to know your skin by doing monthly self-exams.

How to spot skin cancer

Before you can spot skin cancer, you need to know what it looks like. Each type of skin cancer appears somewhat different.

Melanoma is the most serious type of skin cancer and the one you really need to catch early. The signs of melanoma follow the ABCDE rule:

  • Asymmetry: The two sides of the mole or growth don’t match each other.
  • Border: The edges are uneven or ragged, or they blend into the surrounding skin.
  • Color: There is more than one color in the spot, which may include brown, black, pink, white, blue, or red.
  • Diameter: The growth measures more than 1/4 inch across — about the size of a pencil eraser.
  • Evolving: The spot has changed color, size, or shape.

Basal cell cancers look like:

  • a raised, reddish patch that might itch
  • a pink or red translucent or shiny bump
  • a bump with raised edges and a dip in the middle
  • a flat, pale-colored scar
  • an open sore that doesn’t heal, or that heals and then comes back

Squamous cell cancers look like:

  • a scaly patch that may crust or bleed
  • an open sore that doesn’t heal, or that heals and then comes back
  • a bump, sometimes with a dip in the middle
  • a wart-like growth

How to do a skin check

Here’s a step-by-step guide to self-screening for skin cancer. This whole process should take no more than 10 minutes once you get used to doing it.

1. Assemble these tools:

  • full-length mirror
  • hand mirror
  • bright light
  • chair or stool
  • piece of paper and pencil to document any growths you find (The American Academy of Dermatology has a “mole map” you can use as a guide.)

2. Standing at the mirror, check your face — especially your mouth, lips, nose, ears, and behind your ears.

3. Move your hair aside with a comb or hair dryer and check your scalp. Get a friend or family member to help if you can’t see your scalp.

4. Check your hands and arms. Look at the back of each hand, your palms, and the skin between your fingers and under your fingernails. Examine both sides of your arms by bending your elbows. Also look at your underarms.

5. Check your neck, chest, belly, and sides. Women should also look underneath their breasts.

6. Stand with your back to the full-length mirror and hold the hand mirror in front of you to check behind your neck, your shoulders, and your back. Then look at your buttocks and the backs of your legs.

7. Sit on a chair or stool and examine your genital area. Look over the front of your legs, your feet (soles and tops), and the skin between your toes.

8. Draw a picture or write a description of any moles you find. Cross-reference that description during your next skin self-exam.

When to call your doctor

Check your skin once a month. Call your dermatologist if you find any:

  • new spots
  • spots that have changed color, size, or shape
  • sores that don’t heal or that have healed and come back
  • spots that itch or hurt
  • spots that ooze, crust over, or bleed

If you have a history of skin cancer, also make an appointment to see your dermatologist once every six months or year for a checkup.