Skin Cancer Screening (PDQ®)
Last modified: 2018-02-23
Last downloaded: 2018-04-21
What is screening?
Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormaltissue or cancer is found early, it may be easier to treat. By the time symptoms appear, cancer may have begun to spread.
Scientists are trying to better understand which people are more likely to get certain types of cancer. They also study the things we do and the things around us to see if they cause cancer. This information helps doctors recommend who should be screened for cancer, which screening tests should be used, and how often the tests should be done.
It is important to remember that your doctor does not necessarily think you have cancer if he or she suggests a screening test. Screening tests are given when you have no cancer symptoms.
If a screening test result is abnormal, you may need to have more tests done to find out if you have cancer. These are called diagnostic tests.
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General Information About Skin Cancer
Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.
The skin is the body's largest organ. It protects against heat, sunlight, injury, and infection. Skin also helps control body temperature and stores water, fat, and vitamin D. The skin has several layers, but the two main layers are the epidermis (top or outer layer) and the dermis (lower or inner layer). Skin cancer begins in the epidermis, which is made up of three kinds of cells:
- Squamous cells: Thin, flat cells that form the top layer of the epidermis. Cancer that forms in squamous cells is called squamous cell carcinoma of the skin.
- Basal cells: Round cells under the squamous cells. Cancer that forms in basal cells is called basal cell carcinoma.
- Melanocytes: Found in the lower part of the epidermis, these cells make melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment and cause the skin to tan, or darken. Cancer that forms in melanocytes is called melanoma.
Nonmelanoma skin cancer is the most common cancer in the United States.
Basal cell carcinoma and squamous cell carcinoma of the skin are also called nonmelanoma skin cancer and are the most common forms of skin cancer. Most basal cell and squamous cell skin cancers can be cured.
Melanoma is more likely to spread to nearby tissues and other parts of the body and can be harder to cure. Melanoma is easier to cure if the tumor is found before it spreads to the dermis (inner layer of skin). Melanoma is less likely to cause death when it is found and treated early.Anatomy of the skin, showing the epidermis, dermis, and subcutaneous tissue. Melanocytes are in the layer of basal cells at the deepest part of the epidermis.
In the United States, the number of cases of nonmelanoma skin cancer seems to have increased in recent years. The number of cases of melanoma has increased over the last 30 years. Part of the reason for these increases may be that people are more aware of skin cancer. They are more likely to have screening exams and do self-exams. As a result, they are more likely to be diagnosed with skin cancer.
From 2006 to 2015, the number of deaths from melanoma decreased slightly among men and women.
The number of cases of childhood melanoma diagnosed in the United States is low, but increasing over time. The number of childhood deaths from melanoma has stayed about the same.
See the following PDQ summaries for more information about skin cancer:
Different factors increase or decrease the risk of skin cancer.
For information about risk and protective factors for skin cancer, see the PDQ summary on Skin Cancer Prevention.
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Skin Cancer Screening
Tests are used to screen for different types of cancer.
Some screening tests are used because they have been shown to be helpful both in finding cancers early and in decreasing the chance of dying from these cancers. Other tests are used because they have been shown to find cancer in some people; however, it has not been proven in clinical trials that use of these tests will decrease the risk of dying from cancer.
Scientists study screening tests to find those with the fewest risks and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) decreases a person's chance of dying from the disease. For some types of cancer, finding and treating the disease at an early stage may result in a better chance of recovery.
Clinical trials that study cancer screening methods are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI website.
Having a skin exam to screen for skin cancer has not been shown to decrease your chance of dying from skin cancer.
During a skin exam a doctor or nurse checks the skin for moles, birthmarks, or other pigmented areas that look abnormal in color, size, shape, or texture. Skin exams to screen for skin cancer have not been shown to decrease the number of deaths from the disease.
Regular skin checks by a doctor are important for people who have already had skin cancer. If you are checking your skin and find a worrisome change, you should report it to your doctor.
If an area on the skin looks abnormal, a biopsy is usually done. The doctor will remove as much of the suspicious tissue as possible with a localexcision. A pathologist then looks at the tissue under a microscope to check for cancer cells. Because it is sometimes difficult to tell if a skin growth is benign (not cancer) or malignant (cancer), you may want to have the biopsy sample checked by a second pathologist.
Most melanomas in the skin can be seen by the naked eye. Usually, melanoma grows for a long time under the top layer of skin (the epidermis) but does not grow into the deeper layer of skin (the dermis). This allows time for skin cancer to be found early. Melanoma is easier to cure if it is found before it spreads.
Other screening tests are being studied in clinical trials.
Screening clinical trials are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI website.
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Risks of Skin Cancer Screening
Screening tests have risks.
Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Before having any screening test, you may want to discuss the test with your doctor. It is important to know the risks of the test and whether it has been proven to reduce the risk of dying from cancer.
The risks of skin cancer screening tests include the following:
Screening test results may appear to be normal even though cancer is present. A person who receives a false-negative test result (one that shows there is no cancer when there really is) may delay getting medical care even if there are symptoms.
Screening test results may appear to be abnormal even though no cancer is present. A false-positive test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually followed by more tests (such as a biopsy), which also have risks.
When a skin biopsy is done, the doctor will try to leave the smallest scar possible, but there is a risk of scarring and infection.
Talk to your doctor about your risk for skin cancer and your need for screening tests.
Back to Top Source: The National Cancer Institute's Physician Data Query (PDQ®) Cancer Information Summaries ( http://www.cancer.gov/cancertopics/pdq)