Description of the Evidence
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Note: Separate PDQ summaries on Skin Cancer Prevention, Skin Cancer Treatment, and Levels of Evidence for Cancer Screening and Prevention Studies are also available.Interventions
The only widely proposed screening procedure for skin cancer is visual examination of the skin, including both self-examination and clinical examination.Benefits
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.
Magnitude of Effect: Not applicable (N/A).
- Study Design: Evidence obtained from a single case-control study.
- Internal Validity: Poor.
- Consistency: 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, and the possibility of misdiagnosis of a benign lesion as malignant.
Magnitude of Effect: Unknown.
- 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.
- External Validity: Fair.
Description of the Evidence
Incidence and mortality
There are three main types of skin cancer:
- Basal cell carcinoma.
- Squamous cell carcinoma (together with basal cell carcinoma referred to as nonmelanoma skin cancer).
Basal cell carcinoma and squamous cell carcinoma are the most common forms of skin cancer but have substantially better prognoses than the less common, generally more aggressive melanoma.
Nonmelanoma skin cancer is the most commonly occurring cancer in the United States. Its incidence appears to be increasing in some  but not all  areas of the United States. Overall U.S. incidence rates have likely been increasing for a number of years. At least some of this increase may be attributable to increasing skin cancer awareness and resulting increasing investigation and biopsy of skin lesions. A precise estimate of the total number and incidence rate of nonmelanoma skin cancer is not possible, because reporting to cancer registries is not required. However, based on Medicare fee-for-service data extrapolated to the U.S. population, it has been estimated that the total number of persons treated for nonmelanoma skin cancers in 2006 was about 2,152,500.[3,4] That number would exceed all other cases of cancer estimated by the American Cancer Society for that year, which was about 1.4 million.
Melanoma is a reportable cancer in U.S. cancer registries, so there are more reliable estimates of incidence than is the case with nonmelanoma skin cancers. In 2013, it is estimated that 76,690 individuals in the United States will be diagnosed with melanoma and approximately 9,480 will die of it. The incidence of melanoma has been increasing for at least 30 years. From 2005 to 2009, melanoma mortality rates decreased in whites younger than 50 years by 2.8% per year in men and by 2.0 % per year in women. However, the rates have been increasing by 1.1% per year in white men aged 50 years and older, and have been stable in white women aged 50 years and older during this same time period.
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.Risk Factors
Epidemiologic evidence suggests that exposure to UV radiation and the sensitivity of an individual’s skin to UV radiation are risk factors for skin cancer, although the type of exposure (high-intensity and short-duration vs. chronic exposure) and pattern of exposure (continuous vs. intermittent) may differ among the three main types of skin cancer.[7-9] In addition, the immune system may play a role in pathogenesis of skin cancers. Organ-transplant recipients receiving immunosuppressive drugs are at elevated risk of skin cancers, particularly squamous cell cancers (SCC). Arsenic exposure also increases the risk of cutaneous SCC.[10,11]
The incidence of melanoma rises rapidly in Caucasians after age 20 years. Fair-skinned individuals exposed to the sun are at higher risk. 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.Accuracy of Making a Clinical Diagnosis of Melanoma
A systematic review of 32 studies that compared the accuracy of dermatologists and primary care physicians in making a clinical diagnosis of melanoma concluded that there was no statistically significant difference in accuracy. However, the results were inconclusive, owing to small sample sizes and study design weaknesses. In addition, differentiating between benign and malignant melanocytic tumors during histologic examination of biopsy specimens has been shown to be inconsistent 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.Evidence of Benefit Associated With Screening
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.
A systematic review of skin cancer screening examined evidence available through mid-2005 and concluded that direct evidence of improved health outcomes associated with skin cancer screening is lacking.
However, this does not mean that skin cancers (whether melanoma or nonmelanoma) are unimportant or can be neglected without adverse consequences. When neglected, skin cancers can be disfiguring and/or cause death. Skin cancers are easily detected clinically and are often cured by excisional biopsy alone.
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. 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 effects may have been the result of study biases, which frequently affect case-control study designs.
A population-based trial using cluster randomization to determine the effect of skin screening on melanoma mortality was initiated in Queensland, Australia. Intervention communities were randomly assigned to receive a 3-year program targeting adults older than age 30 years. The program consisted of:
- Community education and promotion of self-screening.
- General practitioner education about screening and training in the diagnosis of melanoma.
- Free skin cancer screening clinics.
Matched control communities received usual care. Originally designed to include 44 matched communities followed for 15 years, the trial lost its funding after its initial pilot phase in 18 communities (population 63,035). Although the pilot phase established feasibility of community-based programs, no health outcomes were reported. In the study, 16,383 whole-body skin examinations were reported in the intervention communities, resulting in a referral rate of 14.1% (18.2% for people older than age 50 years). Thirty-three melanomas were diagnosed, 13 of which were in situ. The estimated specificity for melanoma was 86.1%, with a positive predictive value (PPV) of 2.5%. The PPVs for squamous cell and for basal cell cancers were 7.2% and 19.3%, respectively. Negative screens were not followed up, and the sensitivity of skin examination was not reported.Evidence of Harm Associated With Screening
Harms have not been well studied or reported in quantitative terms. However, visual examination of the skin in asymptomatic individuals may lead to unavoidable adverse 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, and the possibility of misdiagnosis of a benign lesion as malignant. (Refer to the Accuracy of Making a Clinical Diagnosis of Melanoma section of this summary for more information.)References
- Athas WF, Hunt WC, Key CR: Changes in nonmelanoma skin cancer incidence between 1977-1978 and 1998-1999 in Northcentral New Mexico. Cancer Epidemiol Biomarkers Prev 12 (10): 1105-8, 2003. [PUBMED Abstract]
- Harris RB, Griffith K, Moon TE: Trends in the incidence of nonmelanoma skin cancers in southeastern Arizona, 1985-1996. J Am Acad Dermatol 45 (4): 528-36, 2001. [PUBMED Abstract]
- Rogers HW, Weinstock MA, Harris AR, et al.: Incidence estimate of nonmelanoma skin cancer in the United States, 2006. Arch Dermatol 146 (3): 283-7, 2010. [PUBMED Abstract]
- American Cancer Society.: Cancer Facts and Figures 2013. Atlanta, Ga: American Cancer Society, 2013. Available online. Last accessed May 2, 2013.
- American Cancer Society.: Cancer Facts and Figures 2006. Atlanta, Ga: American Cancer Society, 2006. Also available online. Last accessed February 15, 2013.
- Welch HG, Woloshin S, Schwartz LM: Skin biopsy rates and incidence of melanoma: population based ecological study. BMJ 331 (7515): 481, 2005. [PUBMED Abstract]
- Koh HK: Cutaneous melanoma. N Engl J Med 325 (3): 171-82, 1991. [PUBMED Abstract]
- Preston DS, Stern RS: Nonmelanoma cancers of the skin. N Engl J Med 327 (23): 1649-62, 1992. [PUBMED Abstract]
- English DR, Armstrong BK, Kricker A, et al.: Case-control study of sun exposure and squamous cell carcinoma of the skin. Int J Cancer 77 (3): 347-53, 1998. [PUBMED Abstract]
- Thomas VD, Aasi SZ, Wilson LD, et al.: Cancer of the skin. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds.: Cancer: Principles and Practice of Oncology. Vols. 1 & 2. 8th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2008, pp 1863-87.
- Le Mire L, Hollowood K, Gray D, et al.: Melanomas in renal transplant recipients. Br J Dermatol 154 (3): 472-7, 2006. [PUBMED Abstract]
- Gandini S, Sera F, Cattaruzza MS, et al.: Meta-analysis of risk factors for cutaneous melanoma: I. Common and atypical naevi. Eur J Cancer 41 (1): 28-44, 2005. [PUBMED Abstract]
- Chen SC, Bravata DM, Weil E, et al.: A comparison of dermatologists' and primary care physicians' accuracy in diagnosing melanoma: a systematic review. Arch Dermatol 137 (12): 1627-34, 2001. [PUBMED Abstract]
- Farmer ER, Gonin R, Hanna MP: Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists. Hum Pathol 27 (6): 528-31, 1996. [PUBMED Abstract]
- Friedman RJ, Rigel DS, Kopf AW: Early detection of malignant melanoma: the role of physician examination and self-examination of the skin. CA Cancer J Clin 35 (3): 130-51, 1985 May-Jun. [PUBMED Abstract]
- Blois MS, Sagebiel RW, Abarbanel RM, et al.: Malignant melanoma of the skin. I. The association of tumor depth and type, and patient sex, age, and site with survival. Cancer 52 (7): 1330-41, 1983. [PUBMED Abstract]
- Wolff T, Tai E, Miller T: Screening for skin cancer: an update of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 150 (3): 194-8, 2009. [PUBMED Abstract]
- MacKie RM, Hole D: Audit of public education campaign to encourage earlier detection of malignant melanoma. BMJ 304 (6833): 1012-5, 1992. [PUBMED Abstract]
- Berwick M, Begg CB, Fine JA, et al.: Screening for cutaneous melanoma by skin self-examination. J Natl Cancer Inst 88 (1): 17-23, 1996. [PUBMED Abstract]
- Elwood JM: Skin self-examination and melanoma. J Natl Cancer Inst 88 (1): 3-5, 1996. [PUBMED Abstract]
- Aitken JF, Elwood JM, Lowe JB, et al.: A randomised trial of population screening for melanoma. J Med Screen 9 (1): 33-7, 2002. [PUBMED Abstract]
- Lowe JB, Ball J, Lynch BM, et al.: Acceptability and feasibility of a community-based screening programme for melanoma in Australia. Health Promot Int 19 (4): 437-44, 2004. [PUBMED Abstract]
- Aitken JF, Janda M, Elwood M, et al.: Clinical outcomes from skin screening clinics within a community-based melanoma screening program. J Am Acad Dermatol 54 (1): 105-14, 2006. [PUBMED Abstract]
Changes to This Summary (03/01/2013)
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.
Added American Cancer Society as reference 4.
Updated statistics with estimated new cases and deaths for 2013.
This summary is written and maintained by the PDQ Screening and Prevention Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ NCI's Comprehensive Cancer Database pages.
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Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about skin cancer screening. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.Reviewers and Updates
This summary is reviewed regularly and updated as necessary by the PDQ Screening and Prevention Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).
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National Cancer Institute: PDQ® Skin Cancer Screening. Bethesda, MD: National Cancer Institute. Date last modified <MM/DD/YYYY>. Available at: http://cancer.gov/cancertopics/pdq/screening/skin/HealthProfessional. Accessed <MM/DD/YYYY>.
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