What Is Skin Cancer?

Skin cancer is the most common form of cancer. It occurs when there is an irregular growth of skin cells. The cells are also how physicians identify the type of skin cancer.

The best way to understand skin cancer is to understand its different types and how they affect the body.

Types of skin cancer

Basal cell carcinoma

Basal cell carcinoma begins in the basal cells, which are the skin cells that replace old cells in the lower level of the epidermis. This type of skin cancer usually appears on the surface of the skin.

Typically, basal cell carcinoma doesn’t spread to other areas of the body. In rare cases where it does, it can be life threatening.

According to the American Cancer Society (ACS), around 80 percent Trusted Source of all skin cancers are basal cell cancers.

Squamous cell cancer

Squamous cell cancer affects the cells on the outermost part of the epidermis.

Squamous cells can also be found in areas like the lungs and mucous membranes. When squamous cell cancer forms in the skin, it’s known as cutaneous squamous cell cancer.

This type of cancer is most commonly found on areas of the body frequently exposed to ultraviolet (UV) sunlight. It’s a very treatable condition, but it can become life threatening without treatment.

The Skin Cancer Foundation says that squamous cell cancer is the second most common type of skin cancer.

According to the ACS, doctors diagnose an estimated 5.4 million Trusted Source basal and squamous cell cancers each year. They’re most likely to develop on areas of your body that get the most sun, like your head and neck.


Another category of skin cancer is melanoma, which accounts for about 1 percent Trusted Source of all skin cancers. This type of cancer develops from cells that give your skin color. These cells are known as melanocytes. Noncancerous moles are formed by melanocytes but can become cancerous.

Melanomas can develop anywhere in your body. They are more common Trusted Source on the chest and back in men and on the legs in women.

Most melanomas are treatable when caught early. However, without treatment, they can spread to other parts of your body and become harder to treat. In addition, melanomas are more likely to spread than basal and squamous cell skin cancers.

Merkel cell skin cancer

Merkel cell skin cancer is a rare form of skin cancer caused by an overgrowth of Merkel cells. According to a 2019 review Trusted Source, Merkel cells are a specialized kind of cell found in the epidermis.

A 2021 review showed an estimated 1,500 cases of Merkel cell cancer reported annually in the United States. It appears to occur more in men than in women, and more in white people.

Although uncommon, it is very dangerous since it can quickly spread to other parts of the body.

Lymphoma of the skin

The body has white blood cells that work as a part of the immune system to defend against infection and disease. These cells are also known as lymphocytes.

When the cells start to grow irregularly on the skin, it’s called a skin lymphoma. The ACS Trusted Source says this is also known as a cutaneous lymphoma.

Kaposi sarcoma

Kaposi sarcoma (KS) appears as red, brown, or purple patches or tumors on the skin. The areas are also known as lesions Trusted Source.

KS lesions typically appear Trusted Source on the legs, feet, or face. Lesions can also appear in the genital area, mouth, or lymph nodes. When they remain on the surface, you may not experience any symptoms.

However, KS lesions can spread inside your body, like to the throat or stomach. When they do this, they can cause bleeding and become life threatening.

Actin keratosis

These are often small patches of red, pink, or brown skin. They’re not cancerous, but are considered a form of precancer. Without treatment, these skin lesions may develop into squamous cell carcinoma.

Symptoms of skin cancer

Skin cancers aren’t all identical, and they may not cause many initial symptoms. Still, unusual changes to your skin can be a warning sign for the different types of cancer. Being alert for changes to your skin may help you get a diagnosis earlier.

Watch out for signs of skin cancer, including:

  • Skin lesions. A new mole, unusual growth, bump, sore, scaly patch, or dark spot develops and doesn’t disappear.
  • Asymmetry. The two halves of a lesion or mole aren’t identical.
  • Border. Lesions have ragged, uneven edges.
  • Color. A spot has an unusual color, such as white, pink, black, blue, or red. It could also have more than one color within a lesion.
  • Diameter. The size is larger than 1/4 inch or about the size of a pencil eraser.
  • Evolving. You can detect that the mole changes in any way, such as the size, shape, color, or symptoms like itching, pain, or bleeding.

It’s best to know all the possible warning signs if you think you have a spot on your skin that may be skin cancer.

Causes and risk factors of skin cancer

Skin cancer occurs when mutations develop in the DNA of your skin cells. These mutations cause skin cells to grow uncontrollably and form a mass of cancer cells.

Many of the causes of skin cancer are unclear. Most moles don’t turn into melanomas, and researchers aren’t sure why some do.

However, risk factors may make you more prone to developing skin cancers, like melanoma.

UV light exposure

The Centers for Disease Control and Prevention (CDC)Trusted Source says exposure to UV light is a significant risk factor for many types of skin cancer. Sources of UV light exposure include:

  • the sun
  • tanning beds
  • sun lamps

UV rays damage your skin cells. When the damage causes an overgrowth of cells, skin cancer develops.


As mentioned before, moles don’t always indicate skin cancer. However, they are more likely to develop into melanoma when you have many of them.

Light skin, light hair, and freckling

People with lighter skin are at greater risk of skin cancer, especially those with:

  • naturally red or blonde hair
  • blue or green eyes
  • light skin that tends to burn or freckle easily in the sun

Family history of skin cancer

If your parents, siblings, or children receive a diagnosis of melanoma, Cancer Research UK says you are at a higher risk. A 2015 study Trusted Source suggests this could be due to a shared lifestyle of being in the sun, everyone sharing a light skin tone, or gene changes in the family.

If you do have a family history of skin cancer, experts suggest you:

  • Perform self-skin checks once per month.
  • Visit your dermatologist regularly for skin checks.
  • Prioritize the use of sunscreen and other forms of sun protection.
  • Avoid tanning beds and sun lamp exposure.

History of skin cancer

If you’ve had skin cancer before, the chances are higher that you will experience it again.

A 2018 study of 969 participants with skin cancer found that 17 percent Trusted Source developed recurring skin cancer, especially if they were older adults. The alarming statistic shows the importance of regular follow-up visits with your doctor to monitor any reoccurrence carefully.

Also, it can even be a different type of skin cancer the next time. For example, if you have had squamous cell skin cancer, you are more likely to get melanoma.

Weakened immune system

When other diseases or health treatments cause damage to your immune system, the chances are higher that you will develop skin cancer.

You might have a weakened immune system if you:

  • undergo chemotherapy
  • take certain medications
  • have an autoimmune disease that causes a weakened immune system

Older age

Even though skin cancer is seen in children and young adults, it is most common in people over 30 years old.

Treatments for skin cancer

Your recommended treatment plan will depend on different factors. These include the cancer’s:

  • size
  • location
  • type
  • stage

After considering these factors, your healthcare team may recommend one or more of the following treatments:

  • Cryosurgery. The growth is frozen using liquid nitrogen and destroys the tissue as it thaws.
  • Excisional surgery. The physician cuts out the growth and some healthy skin surrounding it.
  • Mohs surgery. The growth is removed layer by layer during this procedure. Each layer is examined under a microscope until no irregular cells are visible.
  • Curettage and electrodesiccation. A long spoon-shaped blade scrapes away the cancer cells, and the remaining cells burn by an electric needle.
  • Chemotherapy. This treatment can be taken orally, applied topically, or injected with a needle or intravenous (IV) line to kill the cancer cells.
  • Photodynamic therapy. Laser light and drugs destroy the cancer cells.
  • Radiation. High powered energy beams kill the cancer cells.
  • Biological therapy. Biological treatments stimulate your immune system to fight cancer cells.
  • Immunotherapy. Medications are used to stimulate Trusted Source your immune system to kill the cancer cells.

Skin cancer stages

To determine a skin cancer’s stage or severity, your doctor will factor in:

  • how large the tumor is
  • if it has spread to your lymph nodes
  • if it has spread to other parts of the body

Skin cancers are divided into two main groups for staging purposes, according to Stanford Health Care. These are nonmelanoma skin cancer and melanoma.

Nonmelanoma skin cancers include basal cell and squamous cell cancers.

  • Stage 0. The cancer cells have not spread beyond the outermost layer of skin, the epidermis.
  • Stage 1. The cancer may have spread to the next layer of skin, the dermis, but it is no longer than 2 centimeters.
  • Stage 2. The tumor is larger than 2 centimeters, but it has not spread to nearby sites or lymph nodes.
  • Stage 3. The cancer has spread from the primary tumor to nearby tissue or bone, and it is larger than 3 centimeters. It also typically hasn’t spread to distant sites in the body.
  • Stage 4. The cancer has spread beyond the primary tumor site to lymph nodes and bone or tissue. The tumor is also larger than 3 centimeters and may have spread to distant sites.

Melanoma is typically staged using the American Joint Committee on Cancer’s TNM system Trusted Source. This system uses the tumor thickness and depth (T), lymph node spread (N), and metastasis, or cancer spread, (M) to assign a stage. The lower the number, the earlier it is within the stage. Once the TNM categories have been determined, the overall stage can also be determined.

Early stage melanomas are start at 0, or melanoma in situ. They then progress from stages 1 through 4, and split even further using capital letters. Everyone’s experience will be different, but the stages help guide your doctors in determining what kind of care is best for you.

Overall melanoma stages include:

  • Stage 0. This noninvasive type of skin cancer has not penetrated below the epidermis.
  • Stage 1. The cancer may have spread to the second layer of skin, the dermis, but it remains small.
  • Stage 2. The cancer has not spread beyond the original tumor site, but it is larger, thicker, and may have other signs or symptoms. These include scaling, bleeding, or flaking.
  • Stage 3. The cancer has spread or metastasized to your lymph nodes or to nearby skin or tissue.
  • Stage 4. This is the most advanced stage of melanoma. Stage 4 is an indication the cancer has spread beyond the primary tumor and is showing up in lymph nodes, organs, or tissue distant from the original site.

Preventing skin cancer

To lower your risk of skin cancer, avoid exposing your skin to sunlight and other sources of UV radiation for extended periods. For example:

  • Avoid tanning beds and sun lamps.
  • Avoid direct sun exposure when the sun is strongest, from 10 a.m. to 4 p.m., by staying indoors or in the shade during those times.
  • Apply sunscreen and lip balm with a sun protection factor (SPF) of 30 or higher to any exposed skin at least 30 minutes before heading outdoors, and reapply regularly.
  • Wear a wide-brimmed hat and dry, dark, tightly woven fabrics when you’re outside during daylight hours.
  • Wear sunglasses that offer 100 percent ultraviolet B (UVB) and ultraviolet A (UVA) protection.

It’s also important to regularly examine your skin for changes like new growths or spots. Tell your doctor if you notice anything suspicious.

If you develop skin cancer, identification and early treatment can help improve your long-term outlook.

Complications of skin cancer

Potential complications of skin cancer include:

  • recurrence, where your cancer comes back
  • local recurrence, where cancer cells spread to surrounding tissues
  • metastasis, where cancer cells spread to muscles, nerves, or other organs in your body

If you’ve had skin cancer, you’re at heightened risk of developing it again in another location. If your skin cancer recurs, your treatment options will depend on the type, location, and size of cancer, your health, and prior skin cancer treatment history.


As doctors learn more about skin cancers and see more advancement in medical treatment, the outlook for skin cancer in terms of survival is very optimistic.

However, the outlook depends on the type of skin cancer and the individual themselves.


The ACS estimates that the 5-year survival rate for people with melanoma is between 30 and 99 percent Trusted Source, depending on the stage. Earlier stages having a much higher 5-year survival rate. The rate for all stages combined is 93 percent.

Basal and squamous cell

The number of people that die from basal and squamous cell cancer is estimated at 2,000 Trusted Source per year. However, that number continues to drop with every passing year.

Merkel cell

According to the ACS, all combined stages of Merkel cell cancer have a 5-year survival rate of 64 percentTrusted Source, with varying rates based on the stage.

Skin lymphoma

There is no survival rate for lymphoma, since it depends on the type of lymphoma, how far it is advanced, and how well it responds to treatment. Therefore, early detection is key to judging one’s outlook.

Kaposi sarcoma

All combined stages of KS have a 5-year survival rate of 74 percent Trusted Source, with varying rates based on stage.


Skin cancer may be common, but it’s still dangerous. Early detection is crucial, and it helps to know what to look for to find it. Spotting any warning signs of skin cancer improves your outlook and leads to a better response with treatment.

If your doctor doesn’t include skin exams as part of your routine health checkup, it is best to perform your own skin check once per month or visit a dermatologist. However, if your gut tells you something isn’t right, it is best to check with your doctor to be sure.


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