Skin Cancer Screening (PDQ®): Screening - Health Professional Information [NCI]

Overview

Note: Separate PDQ summaries on Skin Cancer Prevention, Skin Cancer Treatment, Genetics of Skin Cancer, 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 by the patient and clinical examination by the health care provider. Mobile phone applications that evaluate skin lesions to detect skin cancer and malignant melanoma have been launched.[1] However, the use of such applications for the assessment of skin cancer has been problematic because of the lack of evidence on the applications' diagnostic accuracy and because these applications have not been studied in large-scale screening programs.[2,3,4] The use of convolutional neural networks to classify images of melanoma and skin cancer is a growing area of research.[5,6,7]

Benefits

The evidence is inadequate to determine whether visual examination of the skin in asymptomatic individuals leads to a reduction in mortality from melanomatous skin cancer. Further, in asymptomatic populations, the effect of visual skin examination on mortality from nonmelanomatous skin cancers is unknown.

Magnitude of Effect: Unknown.

Study Design: Direct evidence limited to a single ecologic study.

Internal Validity: Poor.

Consistency: Not applicable.

External Validity: Poor.

Harms

Based on fair—though unquantified—evidence, visual examination of the skin in asymptomatic individuals may lead to adverse consequences. These include complications of diagnostic or treatment interventions (such as poor cosmetic or functional outcomes) and the psychological effects of being labeled with a potentially fatal disease. Other harmful consequences are 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: Case series, ecologic studies.

Internal Validity: Fair.

Consistency: Fair.

External Validity: Fair.

References:

1. Buechi R, Faes L, Bachmann LM, et al.: Evidence assessing the diagnostic performance of medical smartphone apps: a systematic review and exploratory meta-analysis. BMJ Open 7 (12): e018280, 2017.
2. Kassianos AP, Emery JD, Murchie P, et al.: Smartphone applications for melanoma detection by community, patient and generalist clinician users: a review. Br J Dermatol 172 (6): 1507-1518, 2015.
3. Wolf JA, Moreau JF, Akilov O, et al.: Diagnostic inaccuracy of smartphone applications for melanoma detection. JAMA Dermatol 149 (4): 422-6, 2013.
4. Udrea A, Mitra GD, Costea D, et al.: Accuracy of a smartphone application for triage of skin lesions based on machine learning algorithms. J Eur Acad Dermatol Venereol 34 (3): 648-655, 2020.
5. Hekler A, Utikal JS, Enk AH, et al.: Superior skin cancer classification by the combination of human and artificial intelligence. Eur J Cancer 120: 114-121, 2019.
6. Esteva A, Kuprel B, Novoa RA, et al.: Dermatologist-level classification of skin cancer with deep neural networks. Nature 542 (7639): 115-118, 2017.
7. Phillips M, Marsden H, Jaffe W, et al.: Assessment of Accuracy of an Artificial Intelligence Algorithm to Detect Melanoma in Images of Skin Lesions. JAMA Netw Open 2 (10): e1913436, 2019.

Description of the Evidence

Incidence and Mortality

There are two main types of skin cancer:

• Nonmelanoma skin cancer.
  • Basal cell carcinoma.
  • Squamous cell carcinoma (SCC).
• Melanoma.

Basal cell carcinoma and SCC 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 [1] but not all [2] areas of the United States. Overall U.S. incidence rates have likely been increasing for a number of years.[3,4] At least some of this increase may be attributable to increased skin cancer awareness and resultant increasing investigation and biopsy of skin lesions. A precise estimate of the total number and incidence rate of nonmelanoma skin cancers is not possible because reporting to cancer registries is not required. However, it has been estimated that about 3 million individuals are diagnosed each year.[3,5] That number exceeds all other cases of cancer estimated by the American Cancer Society for 2020, which is about 1.8 million.[5]

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 2020, it is estimated that 100,350 individuals in the United States will be diagnosed with melanoma and approximately 6,850 will die of it. The incidence of melanoma has been increasing for at least 30 years: from 2007 to 2016, the incidence rate increased by 2.2% per year among adults aged 50 years and older; however, data from the same time period indicate that incidence rates decreased by 1.2% per year in individuals younger than 50 years.[5] From 2013 to 2017, mortality rates declined by 5.7% per year in individuals aged 50 years and older and declined by 7.0% per year in individuals younger than 50 years.[5] The long-term rise in incidence rates is caused, at least in part, by screening in clinical settings and self-examination resulting from campaigns to increase skin cancer awareness.

A study of skin biopsy rates in relation to melanoma incidence rates obtained from the Surveillance, Epidemiology, and End Results Program (SEER) 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.[6] A second study that used SEER data between 2002 and 2009 reported similar findings.[7]

The incidence of melanoma has also been increasing in children and adolescents. Between 1998 and 2007, a 2.5% relative yearly incidence increase in melanoma among children and adolescents was observed in SEER databases.[8] During that time, the average annual incidence in this group was exceptionally low (5.4 per 1 million), which may have resulted in spurious trends. Nevertheless, similar trends have been seen in Sweden.[8] In the U.S. study of pediatric melanoma, nearly one-half of the patients had local disease (22% of patients had in situ disease, and 25% of patients had superficial spreading), and nearly one-half of the patients had disease with a thickness of less than one millimeter. Given that mortality from pediatric melanoma had been fairly stable during those years,[9] it is likely that the increase in incidence could be explained, at least in part, by overdiagnosis.

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.[10,11,12] In addition, genetic predisposition and the immune system may play roles in the pathogenesis of skin cancers.[13] Organ-transplant recipients receiving immunosuppressive drugs are at elevated risk of skin cancers, particularly SCC. Arsenic exposure also increases the risk of cutaneous SCC.[14,15]

The incidence of melanoma rises rapidly in whites 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.[16] Individuals with familial dysplastic nevus syndrome or with several dysplastic or atypical nevi are at high (>fivefold) risk of developing melanoma.[13,16]

It is important to note that, for the general population, most melanomas may not arise from preexisting nevi. A meta-analysis of studies published between 1948 and 2016 found that the prevalence of nevus-associated melanomas was only 29%, compared with 71% for the prevalence of de novo melanomas.[17]

Accuracy of Making a Clinical Diagnosis of Melanoma

Observer variability among physicians has been noted in the evaluation of skin lesions and subsequent biopsy specimens. 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.[18] Subsequent studies have noted a higher accuracy for dermatologists in the diagnosis of melanocytic lesions,[19,20] yet there is a shortage of dermatologists to meet the demands of population-level screening.

A study of 187 pathologists who practiced in the United States found that cases of moderately dysplastic nevi to early-stage invasive melanoma had less than 50% agreement with a reference diagnosis defined by consensus of experienced pathologists.[21] At a U.S. population level, it is estimated that 82.8% (95% confidence interval, 81.0%–84.5%) of melanocytic skin biopsy diagnoses would be verified if they were reviewed by a consensus reference panel of experienced pathologists.[21] In addition, differentiating between benign and malignant melanocytic tumors during histologic examinations of biopsy specimens has been shown to be inconsistent, even in the hands of experienced dermatopathologists.[22,23] This variability in the diagnosis of melanocytic lesions undermines the results of studies that examine 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.[22,23,24] A standardized approach to pathologists' classifying of the interpretations of melanocytic skin lesions may also reduce confusion and improve communication between clinicians.[21,23,25,26]

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 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.[27]

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.[28]

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.[29] An updated review published in 2016 found limited evidence that skin cancer screening reduces melanoma mortality.[30,31]

No randomized trials evaluating the efficacy of skin cancer screening on mortality have been completed. A population-based trial (using cluster randomization) to determine the effect of skin cancer screening on melanoma mortality was initiated in Queensland, Australia, but lost its funding after the initial pilot phase, and no health outcomes were ever reported.[32]

Two ecological studies have been conducted using data from Germany. The first was a pilot project conducted in 2003 and 2004, in which a skin cancer screening program was implemented in one federal state. Suggestion of a reduction in melanoma mortality with screening led to the establishment of countywide skin cancer screening programs in 2008.[33,34] The programs offered a whole-body skin exam once every 2 years for individuals older than 35 years. The second ecological study compared the melanoma mortality experience in Germany with the melanoma mortality experience of subregions of 22 European countries—none of which had organized screening programs—for the years 2000 to 2013. After adjustment for potential confounders, Germany and the 22 European regions had similar malignant mortality rates, suggesting no benefit of screening.[35]

Evidence of Harms Associated With Screening

Harms have not been well studied or reported in quantitative terms, but the potential for adverse consequences from skin cancer screening exists. In the SCREEN pilot project in Germany, 4.4% of all screened participants underwent a skin excision for a suspicious lesion, but the majority of biopsies did not result in a cancer diagnosis. The detection rate was especially affected by age. One case of melanoma was detected per 28 excisions overall (for both men and women), while 52 skin excisions were required to detect one melanoma in men aged 20 to 34 years.[36]

Visual examination of the skin in asymptomatic individuals may lead to cosmetic or functional complications of diagnostic or treatment interventions and the psychological effects of being labeled with a potentially fatal disease, although robust data on the frequency of such events are lacking. Other harmful consequences are overdiagnosis, leading to the detection of biologically benign disease that would otherwise go undetected,[6,7,37] 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:

1. 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.
2. 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.
3. 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.
4. Leiter U, Eigentler T, Garbe C: Epidemiology of skin cancer. Adv Exp Med Biol 810: 120-40, 2014.
5. American Cancer Society: Cancer Facts and Figures 2020. Atlanta, Ga: American Cancer Society, 2020. Available online. Last accessed October 6, 2020.
6. Welch HG, Woloshin S, Schwartz LM: Skin biopsy rates and incidence of melanoma: population based ecological study. BMJ 331 (7515): 481, 2005.
7. Weinstock MA, Lott JP, Wang Q, et al.: Skin biopsy utilization and melanoma incidence among Medicare beneficiaries. Br J Dermatol 176 (4): 949-954, 2017.
8. Austin MT, Xing Y, Hayes-Jordan AA, et al.: Melanoma incidence rises for children and adolescents: an epidemiologic review of pediatric melanoma in the United States. J Pediatr Surg 48 (11): 2207-13, 2013.
9. Lewis KG: Trends in pediatric melanoma mortality in the United States, 1968 through 2004. Dermatol Surg 34 (2): 152-9, 2008.
10. Koh HK: Cutaneous melanoma. N Engl J Med 325 (3): 171-82, 1991.
11. Preston DS, Stern RS: Nonmelanoma cancers of the skin. N Engl J Med 327 (23): 1649-62, 1992.
12. 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.
13. Hawkes JE, Truong A, Meyer LJ: Genetic predisposition to melanoma. Semin Oncol 43 (5): 591-597, 2016.
14. 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.
15. Le Mire L, Hollowood K, Gray D, et al.: Melanomas in renal transplant recipients. Br J Dermatol 154 (3): 472-7, 2006.
16. 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.
17. Pampena R, Kyrgidis A, Lallas A, et al.: A meta-analysis of nevus-associated melanoma: Prevalence and practical implications. J Am Acad Dermatol 77 (5): 938-945.e4, 2017.
18. 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.
19. Chen SC, Pennie ML, Kolm P, et al.: Diagnosing and managing cutaneous pigmented lesions: primary care physicians versus dermatologists. J Gen Intern Med 21 (7): 678-82, 2006.
20. Corbo MD, Wismer J: Agreement between dermatologists and primary care practitioners in the diagnosis of malignant melanoma: review of the literature. J Cutan Med Surg 16 (5): 306-10, 2012 Sep-Oct.
21. Elmore JG, Barnhill RL, Elder DE, et al.: Pathologists' diagnosis of invasive melanoma and melanocytic proliferations: observer accuracy and reproducibility study. BMJ 357: j2813, 2017.
22. 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.
23. Lott JP, Elmore JG, Zhao GA, et al.: Evaluation of the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) classification scheme for diagnosis of cutaneous melanocytic neoplasms: Results from the International Melanoma Pathology Study Group. J Am Acad Dermatol 75 (2): 356-63, 2016.
24. Piepkorn MW, Longton GM, Reisch LM, et al.: Assessment of Second-Opinion Strategies for Diagnoses of Cutaneous Melanocytic Lesions. JAMA Netw Open 2 (10): e1912597, 2019.
25. Piepkorn MW, Barnhill RL, Elder DE, et al.: The MPATH-Dx reporting schema for melanocytic proliferations and melanoma. J Am Acad Dermatol 70 (1): 131-41, 2014.
26. Radick AC, Reisch LM, Shucard HL, et al.: Terminology for melanocytic skin lesions and the MPATH-Dx classification schema: A survey of dermatopathologists. J Cutan Pathol : , 2020.
27. 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.
28. 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.
29. 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.
30. Wernli KJ, Henrikson NB, Morrison CC, et al.: Screening for Skin Cancer in Adults: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA 316 (4): 436-47, 2016.
31. Bibbins-Domingo K, Grossman DC, Curry SJ, et al.: Screening for Skin Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 316 (4): 429-35, 2016.
32. Aitken JF, Elwood JM, Lowe JB, et al.: A randomised trial of population screening for melanoma. J Med Screen 9 (1): 33-7, 2002.
33. Katalinic A, Waldmann A, Weinstock MA, et al.: Does skin cancer screening save lives? An observational study comparing trends in melanoma mortality in regions with and without screening. Cancer 118 (21): 5395-402, 2012.
34. Eisemann N, Waldmann A, Holleczek B, et al.: Observed and expected mortality in the German skin cancer screening pilot project SCREEN. J Med Screen 25 (3): 166-168, 2018.
35. Kaiser M, Schiller J, Schreckenberger C: The effectiveness of a population-based skin cancer screening program: evidence from Germany. Eur J Health Econ 19 (3): 355-367, 2018.
36. Waldmann A, Nolte S, Geller AC, et al.: Frequency of excisions and yields of malignant skin tumors in a population-based screening intervention of 360,288 whole-body examinations. Arch Dermatol 148 (8): 903-10, 2012.
37. Schoffer O, Schülein S, Arand G, et al.: Tumour stage distribution and survival of malignant melanoma in Germany 2002-2011. BMC Cancer 16 (1): 936, 2016.

Changes to This Summary (12 / 23 / 2020)

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.

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About This PDQ Summary

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.

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PDQ® Screening and Prevention Editorial Board. PDQ Skin Cancer Screening. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/skin/hp/skin-screening-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389300]

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Last Revised: 2020-12-23