- About Screening
- Screening Tests
- Screening Risks
What is screening?
Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormal tissue 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.
Refer to the following PDQ summaries for more information about prevention, diagnosis, and treatment of skin cancer:
- Prevention of Skin Cancer
- Skin Cancer Treatment
- Melanoma Treatment
General Information About Skin CancerSkin 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 (upper 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.
- Basal cells: Round cells under the squamous cells.
- 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, causing the skin to tan, or darken.
Skin cancer is the most common cancer in the United States.
The three most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma. Basal cell carcinoma is the most common and melanoma is the least common skin cancer.
Most basal cell and squamous cell skin cancers can be cured, but people with these types of cancer have a higher risk for developing other skin cancers. Melanoma causes about three fourths of skin cancer deaths in the United States and is the focus of this screening summary.
Skin color and exposure to sunlight can affect the risk of developing melanoma.
Anything that increases your chance of getting a disease is called a risk factor. Risk factors for melanoma include the following:
- Having a fair complexion (blond or red hair, fair skin, freckles, blue eyes).
- Being exposed to natural sunlight or ultraviolet light (such as tanning booths) over long periods of time.
- Being white and older than 20 years.
- Having several large or many small moles.
- Having a family history of unusual moles (atypical nevus syndrome).
- Having a family or personal history of melanoma.
The best defense against skin cancer is protection from sunlight and ultraviolet light. Refer to the PDQ summary on Prevention of Skin Cancer for more information
Skin Cancer ScreeningTests 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 Cancer.gov Web site.Skin examinations are commonly used to screen for melanoma.
Regular examination of the skin by both you and your doctor increases the chance of finding melanoma early. Most melanomas that appear in the skin can be seen by the naked eye. Usually, there is a long period of time when the tumor grows beneath the top layer of skin but does not grow into the deeper skin layers. This period of slow growth allows time for skin cancer to be found early. Skin cancer may be cured if the tumor is found before it spreads deeper. Monthly self-examination of the skin may help find changes that should be reported to a doctor. Regular skin checks by a doctor are important for people who have already had skin cancer.
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 local excision. 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.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 Cancer.gov Web site.
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 melanoma screening tests include the following: Finding melanoma may not improve health or help a person live longer.
Screening may not improve your health or help you live longer if you have advanced melanoma or if it has already spread to other places in your body.
Some cancers never cause symptoms or become life-threatening, but if found by a screening test, the cancer may be treated. It is not known if treatment of these cancers would help you live longer than if no treatment were given, and treatments for cancer may have serious side effects.False-negative test results can occur.
Screening test results may appear to be normal even though melanoma is present. A person who receives a false-negative test result (one that shows there is no cancer when there really is) may delay seeking medical care even if there are symptoms.False-positive test results can occur.
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.A biopsy may cause scarring.
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.
Your doctor can advise you about your risk for skin cancer and your need for screening tests.