Skin Cancer

What is skin cancer?

Skin cancer develops in the cells of the skin and often appears as a lesion. There are several types of skin cancer. 

How common is skin cancer?

Skin cancer is the most common cancer. About one in five people in the United States will be diagnosed with skin cancer in their lifetime.  


What are the types of skin cancer?

There are two types of skin cancers: nonmelanoma and melanoma. Nonmelanoma is the most common. 

Types of nonmelanoma include:

  • Basal cell carcinoma
  • Cutaneous lymphoma
  • Kaposi sarcoma
  • Merkel cell carcinoma
  • Squamous cell carcinoma

Types of melanoma include:

  • Acral lentiginous melanoma
  • Amelanotic melanoma
  • Desmoplastic or neurotropic
  • Lentigo maligna
  • Nodular melanoma
  • Superficial spreading melanoma


Because it’s so common, it is best to know the early signs of skin cancer so you can be sure how to check for skin cancer. 

The first symptom of melanoma is often a change in a mole or the appearance of a new mole. The ABCDE rule can help you tell a normal mole from one that might be melanoma. The rule is: 

  • Asymmetry. One half of the mole does not match the other half.
  • Border irregularity. The edges of the mole are ragged or irregular.
  • Color. The mole has different colors in it. It may be tan, brown, black, red or other colors. Or it may have areas that appear to have lost color.
  • Diameter. The mole is bigger than 6 mm or ¼ inch across, about the size of a pencil eraser. But some melanomas can be smaller.
  • Evolving. A mole changes in size, shape or color.

Other symptoms may include:

  • A mole that hurts, itches or is sore
  • A mole that oozes, bleeds or becomes crusty
  • A mole that looks different from your other moles
  • A sore that doesn't heal
  • A mole or sore that becomes red or swells at its edges or beyond

Risk Factors

What causes skin cancer?

The most common risk factors for melanoma include:

  • Age
  • Artificial tanning
  • Certain inherited conditions, such as xeroderma pigmentosum (XP)
  • Exposure to arsenic or hydrocarbons
  • Exposure to UV rays
  • Family history
  • Having fair skin, light hair or freckles
  • Having many moles
  • Having scars, burns or inflamed skin
  • Human papillomavirus (HPV) infection
  • Past radiation treatment
  • Personal history of skin cancer
  • Smoking
  • Sun exposure
  • Weak immune system

Millions of people are diagnosed with skin cancer in the U.S. each year. Skin cancer is more common as people get older. But skin damage from the sun starts at an early age and builds up over time. Protection should start in childhood to prevent skin cancer later in life.


How to prevent skin cancer

Some skin cancers can be prevented, and some cannot. Melanoma cannot be fully prevented, but taking a few simple steps can help lower your risk.

Here’s what you can do to help reduce your risk of skin cancer:

  • Limit your exposure to the sun between 10 a.m. and 4 p.m. This is when UV rays are strongest. Stay in the shade if you're outside during this time.
  • Apply a generous amount of sunscreen 15 to 30 minutes before you go outside. Use a water-resistant, broad-spectrum sunscreen with a sun protection factor (SPF) of at least 30. Broad-spectrum means the sunscreen protects against both UVA and UVB rays. Apply it to all areas of your body that will be exposed to the sun. Don't forget your feet, neck, ears, and the top of your head.
  • Use lip balm that has an SPF of at least 30.
  • Reapply sunscreen every 2 hours, even on cloudy days. Also reapply every hour after swimming or sweating.
  • Check the expiration date on your sunscreen to make sure it's still effective. Don't use sunscreen that has expired.
  • Wear clothing that covers your body and shades your face. Wear a long-sleeved shirt, pants, and a wide-brimmed hat. Hats should provide shade for the face, ears, and back of the neck. For even better protection, wear clothing with UPF (ultraviolet protection factor).
  • Wear sunglasses with a UV coating. The label should say 100% UVA/UVB protection). This will reduce the amount of UV rays that reach the eye. And it will protect your eyelids and the eye itself.
  • Don’t use sunlamps or tanning beds.

Regular skin self-exams may help you find skin cancer early, when it’s smaller and easier to treat. Become familiar with the way your skin and moles look. Talk with your provider about any bumps, spots or other marks on your skin.


How is skin cancer diagnosed?

A biopsy is the only way to confirm cancer. Tiny pieces of the changed mole or skin are removed and sent to a lab. Then they're tested for cancer cells. Your results should come back in about one week.

After a diagnosis of melanoma, you'll need more tests. These help your providers learn more about your overall health and the cancer. They're used to find out the stage of the cancer.

Once your cancer is staged, your provider will talk with you about what the stage means for your treatment. Be sure to ask your provider to explain the details of your cancer to you in a way you can understand.

Stages of skin cancer

The stage is how much cancer there is and how far it has spread in your body. It's one of the most important things to know when deciding how to treat the cancer. The severity of skin cancer is measured in stages 0 through 4. The higher the number, the more advanced or the more the cancer has spread.

Most nonmelanoma skin cancers are Stage 0 or Stage I and can be easily treated. Stages 3 and 4 are fairly rare.


How is skin cancer treated?

Most skin cancer is curable. Depending on several factors, including what stage your cancer is at, your provider will determine how to treat skin cancer.

Skin cancer may be treated with:

  • Surgery. The goal of surgery is to remove the melanoma but leave as much of the nearby skin as intact as possible. Surgery can also be used to help treat melanoma that has reached the lymph nodes.
  • Radiation therapy. It may be used to help treat melanoma that has come back after a first treatment or has spread to other parts of the body.
  • Chemotherapy (chemo). The goal of chemo is to destroy cancer cells directly to shrink tumors that can’t be removed by surgery or it may be used to kill cells that have spread to other areas of the body, known as metastatic melanoma.
  • ImmunotherapyThe goal of immunotherapy is to boost your body's immune system to shrink advanced melanoma tumors. It might also be used after surgery for some earlier stage melanomas. This is to lower the risk that the cancer will come back. 
  • Mohs surgery. This procedure removes the cancer and as little normal tissue as possible. It’s done in sensitive areas such as the face. During Mohs surgery, you’re given a local anesthetic to numb the area being treated. The cancer is removed from the skin one layer at a time. Each layer is checked under a microscope for cancer. If cancer cells are seen, another layer of skin is removed. Layers are removed until the health care provider doesn’t see any more cancer.


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