Skin Cancer Screening (PDQ®): Screening - Health Professional Information [NCI]
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Skin Cancer Screening
Purpose of This PDQ Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about skin cancer screening. This summary is reviewed regularly and updated as necessary by the PDQ Screening and Prevention Editorial Board.
Information about the following is included in this summary:
- Skin cancer incidence and mortality statistics and information about skin cancer risk factors.
- Skin cancer screening modalities.
- Benefits and harms of skin cancer screening.
This summary is intended as a resource to inform clinicians and other health professionals about currently available skin cancer screening modalities. The PDQ Screening and Prevention Editorial Board uses a formal evidence ranking system in reporting the evidence of benefit and potential harms associated with each screening modality. It does not provide formal guidelines or recommendations for making health care decisions. Information in this summary should not be used as a basis for reimbursement determinations.
This summary is also available in a patient version, which is written in less technical language.
Summary of Evidence
Note: Separate PDQ summaries on Skin Cancer Prevention, Skin Cancer Treatment, and Levels of Evidence for Cancer Screening and Prevention Studies are also available.
The only widely proposed screening procedure for melanomatous skin cancer is visual examination of the skin, including both self examination and clinical examination.
In asymptomatic populations, the effect of visual skin examination on mortality from nonmelanomatous skin cancers is unknown. Further, the evidence is inadequate to determine whether visual examination of the skin in asymptomatic individuals would lead to a reduction in mortality from melanomatous skin cancer.
Description of the Evidence
- STUDY DESIGN: Evidence obtained from a single case-control study.
- INTERNAL VALIDITY: Poor.
- CONSISTENCY: Not applicable (N/A).
- MAGNITUDE OF EFFECTS ON HEALTH OUTCOMES: N/A.
- EXTERNAL VALIDITY: N/A.
Based on fair though unquantified evidence, visual examination of the skin in asymptomatic individuals may lead to unavoidable increases in harmful consequences. These include complications of diagnostic or treatment interventions (including extensive surgery) and the psychological effects of being labeled with a potentially fatal disease. Another harmful consequence is overdiagnosis leading to the detection of biologically benign disease that would otherwise go undetected.
Description of the Evidence
- STUDY DESIGN: Opinions of respected authorities based on clinical experience, descriptive studies, or reports of expert committees.
- INTERNAL VALIDITY: Fair.
- CONSISTENCY: Multiple studies; small number of participants—no consistency.
- MAGNITUDE OF EFFECTS ON HEALTH OUTCOMES: Unknown.
- EXTERNAL VALIDITY: Fair.
Incidence and Mortality
Skin cancer is the most common cancer in the United States, affecting more than 1,000,000 Americans every year. It accounts for more than 10,000 deaths annually.
Skin cancers are easily detected clinically and are often cured by excisional biopsy alone. This does not mean that they are unimportant or can be neglected without adverse consequences. When neglected, they can be disfiguring and/or cause death.
There are three major types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and cutaneous melanoma. Basal cell carcinoma has the highest incidence and melanoma has the lowest. Basal and squamous cell carcinomas have an excellent prognosis, but persons diagnosed with these nonmelanomatous skin cancers are at higher risk for developing additional skin cancers. Melanoma, which is the focus of this summary, accounts for approximately three-fourths of all skin cancer deaths.
Mortality from melanoma increased after the 1970s, especially in white males.[3,4] In the 1990s, melanoma mortality rates stabilized. In 2009, it is estimated that 68,720 individuals are expected to develop melanoma, and about 8,650 are expected to die of this disease. In the United States, observed incidence increased 126% between 1973 and 1995, at a rate of approximately 6% per year, though incidence rates appear also to have stabilized in the 1990s. A study of skin biopsy rates in relation to melanoma incidence rates obtained from the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute indicated that much of the observed increase in incidence between 1986 and 2001 was confined to local disease and was most likely caused by overdiagnosis as a result of increased skin biopsy rates during this period.
The incidence of melanoma rises rapidly in Caucasians after age 20 years. Fair-skinned individuals exposed to the sun are at higher risk. The best defense against skin cancer is protection from the sun and ultraviolet light, though the effectiveness of sunscreens in preventing melanoma has been challenged. (Refer to the PDQ summary on Prevention of Skin Cancer for more information.) Individuals with certain types of pigmented lesions (dysplastic or atypical nevi), with several large nondysplastic nevi, with many small nevi, or with moderate freckling have a twofold to threefold increased risk of developing melanoma. Individuals with familial dysplastic nevus syndrome or with several dysplastic or atypical nevi are at high (>fivefold) risk of developing melanoma.
Evidence of Benefit
The melanoma mortality rate in the United States increased by 1.7% annually between 1973 and 1990, then decreased or stabilized thereafter. The changes in this trend in the 1990s might be due to prevention and/or early detection practices.
More than 90% of melanomas that arise in the skin can be recognized with the naked eye. Very often, there is a prolonged horizontal growth phase during which time the tumor expands centrifugally beneath the epidermis but does not invade the underlying dermis. This horizontal growth phase may provide lead time for early detection. Melanoma is more easily cured if treated before the onset of the vertical growth phase with its metastatic potential.
The probability of tumor recurrence within 10 years after curative resection is less than 10% with tumors less than 1.4 mm in thickness. For patients with tumors less than 0.76 mm in thickness, the likelihood of recurrence is less than 1% in 10 years.
Various observational studies exploring the possibility that melanoma screening may be effective have been reported. An educational campaign in western Scotland, promoting awareness of the signs of suspicious skin lesions and encouraging early self-referral, showed a decrease in mortality rates associated with the campaign. No randomized controlled trials have been performed, however, to assess screening efficacy, though one randomized study is under way in Australia. A case-control study of 650 cases (and 549 controls) diagnosed in Connecticut showed that skin self-examination was associated with reduced melanoma incidence. The authors estimated that monthly skin self-examination might decrease disease-specific mortality by 63%, but the observed incidence effects may have been the result of study biases, which frequently affect case-control study designs.
Differentiating between benign and malignant melanocytic tumors during histologic examination of biopsy specimens has been shown to be unreliable even in the hands of experienced dermatopathologists. This fact undermines results of studies examining screening effectiveness and also may undermine the effectiveness of any screening intervention. Furthermore, this suggests that requesting a second opinion regarding the pathology of biopsy specimens may be important.
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Changes To This Summary (06 / 30 / 2009)
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Updated incidence and mortality estimates for 2009 (cited American Cancer Society as reference 1).
Questions or Comments About This Summary
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- PDQ® - NCI's Comprehensive Cancer Database.
Full description of the NCI PDQ database.
ADDITIONAL PDQ SUMMARIES
- PDQ® Cancer Information Summaries: Adult Treatment
Treatment options for adult cancers.
- PDQ® Cancer Information Summaries: Pediatric Treatment
Treatment options for childhood cancers.
- PDQ® Cancer Information Summaries: Supportive and Palliative Care
Side effects of cancer treatment, management of cancer-related complications and pain, and psychosocial concerns.
- PDQ® Cancer Information Summaries: Screening/Detection (Testing for Cancer)
Tests or procedures that detect specific types of cancer.
- PDQ® Cancer Information Summaries: Prevention
Risk factors and methods to increase chances of preventing specific types of cancer.
- PDQ® Cancer Information Summaries: Genetics
Genetics of specific cancers and inherited cancer syndromes, and ethical, legal, and social concerns.
- PDQ® Cancer Information Summaries: Complementary and Alternative Medicine
Information about complementary and alternative forms of treatment for patients with cancer.
This information is intended mainly for use by doctors and other health care professionals. If you have questions about this topic, you can ask your doctor, or call the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).
Date Last Modified: 2009-06-30