Detection and screening

From Skin Cancer Statistics and Issues
Skin Cancer Stats & Issues > Detection and screening

As melanoma and NMSC skin cancers are often identifiable to the naked eye, skin self-examinations by patients and total-body skin examinations by physicians can lead to earlier detection and a reduction in mortality.[1][2]

Mass screening involves testing across an apparently healthy population in order to identify the early stages of disease in individuals.[3] Currently, population-based screening is not recommended for melanoma or other skin cancers, due to insufficient evidence that it reduces mortality.[4]

Individuals who are concerned about skin cancer or changes in their skin should seek advice from a medical practitioner and discuss their skin cancer risk and need for medical checks or self-examination.


Skin self-examination

The 2009 US Preventive Task Force cited insufficient evidence to be able to assess the benefits of skin self-examination.[5] Cancer Council Australia[4] recommends skin self-examination for those at elevated risk of skin cancer, particularly for those over 40 years of age, outdoor workers, and those with a personal or family history of skin cancer.

Early detection through skin self-examination potentially reduces the risk of advanced melanoma by 63% through early detection of thinner lesions.[2] It is also associated with increased detection of ≤1mm thick lesions,[6] which have a high 95% five-year survival.[1] The 10-year survival rate for thin invasive melanomas is 99% in those younger than 60 years.

High risk individuals are encouraged to regularly check all areas of their skin (including areas not typically exposed to the sun) for suspicious spots/moles (naevi) and to look for changes in shape, colour or size of existing pigmented lesions.[4][7] Individuals concerned about their skin cancer risk, or new or changing skin lesions, should seek advice from a medical practitioner.[4]

Characteristics of suspicious spots/moles are described by 'ABCDE'[7]:

  • Asymmetry,
  • Border irregularity,
  • Colour: variegated (including a surrounding coloured halo)
  • Diameter >6 mm
  • Evolving


3 ABCD.png

Figure 1: 'ABCD' characteristics

Images generously provided by Dr Alvin Chong, Skin & Cancer Foundation Victoria


A general sense of abnormality compared with an individual’s other pigmented lesions can also be a sign of a cancerous lesion - the so-called “ugly duckling” effect.[7][8]


3 Ugly duckling.png

Figure 2: “Ugly duckling” pigmented lesion

Image generously provided by Dr Alvin Chong, Skin & Cancer Foundation Victoria


Modified 'ABCDE' criteria have been proposed for diagnosing paediatric melanomas based on a retrospective study which found that 60% of children under 10 years of age and 40% of 11-19 year olds did not present with typical 'ABCDE' clinical presentation. Cordoro and colleagues recommend using the conventional 'ABCDE' criteria along with the modified version to facilitate diagnosis[9]:

  • Amelanotic (lesions that are red or pink)
  • Bleeding and bump (bleeding and raised lesions)
  • Colour uniformity
  • De novo development and diameter <6mm

The Royal Australian College of General Practitioners recommend that high-risk individuals - those with multiple atypical/dysplastic naevi and a personal history of melanoma/history in a first-degree relative - self-examine every 3 months, and may benefit from self-photography.[7]

The 2011-12 ABS Australian Health Survey estimates that over half (56%) of men regularly check their skin for changes in freckles and moles - slightly less often than for women (61%).[10]

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Mass screening

Mass screening for the general adult population was not recommended by the 2009 US Preventative Services Task Force for the early detection of cutaneous melanoma, basal cell carcinoma, or squamous cell carcinoma.[5] The task force concluded that there was “insufficient evidence to assess the balance of benefits and harms of screening for skin cancer”. More recently a study by Aitken and colleagues has found that clinical whole-body skin examination leads to detection of melanoma tumours at an earlier stage (when the tumour is thinner),[11] which in turn reduces mortality.[1] However the study does not provide information on the costs to the health system.

Skin cancer does not meet population screening guidelines (as produced by the World Health Organization)[12] due to a low mortality rate for non-melanocytic skin cancers (NMSC),[13] and sub-optimal cost-effectiveness and diagnostic accuracy for melanoma.[5]

Therefore, Cancer Council Australia's current recommendation include opportunistic screening and skin self-examination in place of routine population screening.[4]

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Diagnosing skin cancer

Dermatoscopy

3 Dermatoscopes.png

Figure 3: Dermatoscopes

Image generously provided by Dr Alvin Chong, Skin & Cancer Foundation Victoria


Naked-eye clinical diagnosis of cutaneous melanoma has an accuracy rate of only 60%.[14] Therefore dermatoscopy, also known as dermoscopy, (examining lesions using a hand-held microscope) is used in order to improve accuracy in diagnosing pigmented skin lesions.[15] Dermatoscopy has an accuracy of 89% and sensitivity of 82.6% for detecting melanocytic lesions, a sensitivity of 98.6% for basal cell carcinoma and 86.5% for squamous cell carcinoma. Improvement in sensitivity with use of dermatoscopy was higher for melanocytic than non-melanocytic lesions.[16]

The number needed to treat (NNT) is an epidemiological measure used in assessing the effectiveness of a healthcare intervention − in this case a rate of excised melanomas to misdiagnosed benign lesions. Lower numbers needed to treat (NNT) signify a lower rate of misdiagnosed benign lesions to melanomas excised, and therefore signify reduced morbidity and healthcare costs.[17]

A study by Rosendahl and colleagues found that there was an association between higher dermatoscopy use and lower melanoma numbers need to treat (NNTs), indicating fewer misdiagnoses among general practitioners using dermatascopes. However, after adjusting by practice type (dedicated skin cancer practitioner, general practitioner (GP), GP with a special interest in skin cancer) these were no longer significant.[18] This result may be explained in light of a study that found diagnostic accuracy via dermatoscopy significantly depends on the examiner’s degree of experience, as no improvement in diagnosis was noted among inexperienced dermatoscopy users.[14]

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Primary care physicians

Within Australia, skin cancers are the most common cancer managed by general practitioners (GPs), who have historically been the first port of call for patients seeking an examination for skin cancer.[19] GPs are also responsible for the majority of skin cancer excisions, and are increasingly also performing surgical repairs (flap and graft repairs).[20] A study of Australian GPs showed higher diagnostic accuracy among GPs who specialised in skin cancer than GPs within a general practice.[18] However, an earlier study in Queensland reported similar levels of diagnosis accuracy among GPs whether they were working in a skin cancer clinic or not.[21]

Dermatoscopy use[18] and a physician’s level of experience with diagnosing skin cancer[21] have been shown to be the main factors determining diagnostic accuracy.

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Skin cancer clinics

Historically, skin cancer management was performed primarily by general practitioners, but in recent years there has been a rapid increase in the number of skin cancer clinics.[19]

Overall, the majority of skin cancer excisions in Australia are performed by general practitioners.[20] In a study of surgeries performed between 2001-2005, GPs within a general practice performed more excisions of non-melanocytic skin cancers than GPs working in skin cancer clinics, who perform more melanoma excisions. However, melanoma excisions by GPs and skin cancer clinic GPs are similar in Queensland, where GPs have nearly double the national excision rate.[20]

Some concerns have been raised that skin cancer clinics are not accredited against a standard, and that they primarily employ general practitioners who have limited training, with no formal award course offered.[22] It has also been suggested that unnecessary excisions of spots/moles are frequent in skin cancer clinics.[23]

Overall, studies show that NNT in skin cancer clinics compare similarly between GPs in general and more specialised practices.[19][22] Further, diagnostic accuracy (sensitivity) is similar among skin cancer clinics and general practice.[21] However, diagnosis is just one aspect and research into other health outcomes for skin cancer clinics such as effectiveness of treatment and surgical repair are required to be able to fully evaluate Australian skin cancer clinics.[19]

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Dermatologists

A comparison of multiple studies showed that dermatologists have the lowest NNT (therefore lowest rate of misdiagnosis of benign lesions) as compared with general practitioners, doctors with a dedicated skin cancer practice, and doctors working in skin cancer clinics in Australia.[18]


References

  1. 1.0 1.1 1.2 Balch CM, Soong SJ, Atkins MB, Buzaid AC, Cascinelli N, Coit DG, et al. An evidence-based staging system for cutaneous melanoma. CA Cancer J Clin 2004 May;54(3):131-49; quiz 182-4 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15195788.
  2. 2.0 2.1 Berwick M, Begg CB, Fine JA, Roush GC, Barnhill RL. Screening for cutaneous melanoma by skin self-examination. J Natl Cancer Inst 1996 Jan 3;88(1):17-23 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/8847720.
  3. Wilson JM, Jungner YG. [Principles and practice of mass screening for disease]. Bol Oficina Sanit Panam 1968 Oct;65(4):281-393 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/4234760.
  4. 4.0 4.1 4.2 4.3 4.4 Cancer Council Australia. Position statement: Screening and early detection of skin cancer. Sydney, Australia: Cancer Council Australia; 2014 [cited 2016 Oct 12] Available from: http://wiki.cancer.org.au/policy/Position_statement_-_Screening_and_early_detection_of_skin_cancer.
  5. 5.0 5.1 5.2 U.S. Preventive Services Task Force. Screening for skin cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2009 Feb 3;150(3):188-93 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/19189908.
  6. Carli P, De Giorgi V, Palli D, Maurichi A, Mulas P, Orlandi C, et al. Dermatologist detection and skin self-examination are associated with thinner melanomas: results from a survey of the Italian Multidisciplinary Group on Melanoma. Arch Dermatol 2003 May;139(5):607-12 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/12756097.
  7. 7.0 7.1 7.2 7.3 Royal Australian College of General Practitioners. Guidelines for preventive activities in general practice. East Melbourne, Australia; 2012.
  8. Grob JJ, Bonerandi JJ. The 'ugly duckling' sign: identification of the common characteristics of nevi in an individual as a basis for melanoma screening. Arch Dermatol 1998 Jan;134(1):103-4 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/9449921.
  9. Cordoro KM, Gupta D, Frieden IJ, McCalmont T, Kashani-Sabet M. Pediatric melanoma: results of a large cohort study and proposal for modified ABCD detection criteria for children. J Am Acad Dermatol 2013 Jun;68(6):913-25 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/23395590.
  10. Australian Bureau of Statistics. 4364.0 - 2011-2012 Australian Health Survey: Health Service Usage and Health Related Actions. Canberra, Australia: Australian Bureau of Statistics; 2013 Available from: http://www.abs.gov.au/AUSSTATS/abs@.nsf/Lookup/4364.0.55.002Main+Features12011-12?OpenDocument.
  11. Aitken JF, Elwood M, Baade PD, Youl P, English D. Clinical whole-body skin examination reduces the incidence of thick melanomas. Int J Cancer 2010 Jan 15;126(2):450-8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/19609948.
  12. World Health Organization. Screening for various cancers. Geneva, Switzerland; 2008 Available from: www.who.int/cancer/detection/variouscancer/en/.
  13. Clayman GL, Lee JJ, Holsinger FC, Zhou X, Duvic M, El-Naggar AK, et al. Mortality risk from squamous cell skin cancer. J Clin Oncol 2005 Feb 1;23(4):759-65 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15681519.
  14. 14.0 14.1 Kittler H, Pehamberger H, Wolff K, Binder M. Diagnostic accuracy of dermoscopy. Lancet Oncol 2002 Mar;3(3):159-65 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/11902502.
  15. Campos-do-Carmo G, Ramos-e-Silva M. Dermoscopy: basic concepts. Int J Dermatol 2008 Jul;47(7):712-9 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/18613881.
  16. Rosendahl C, Tschandl P, Cameron A, Kittler H. Diagnostic accuracy of dermatoscopy for melanocytic and nonmelanocytic pigmented lesions. J Am Acad Dermatol 2011 Jun;64(6):1068-73 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/21440329.
  17. Argenziano G, Cerroni L, Zalaudek I, Staibano S, Hofmann-Wellenhof R, Arpaia N, et al. Accuracy in melanoma detection: a 10-year multicenter survey. J Am Acad Dermatol 2012 Jul;67(1):54-9 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/21982636.
  18. 18.0 18.1 18.2 18.3 Rosendahl C, Williams G, Eley D, Wilson T, Canning G, Keir J, et al. The impact of subspecialization and dermatoscopy use on accuracy of melanoma diagnosis among primary care doctors in Australia. J Am Acad Dermatol 2012 Nov;67(5):846-52 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/22325462.
  19. 19.0 19.1 19.2 19.3 Wilkinson D, Askew DA, Dixon A. Skin cancer clinics in Australia: workload profile and performance indicators from an analysis of billing data. Med J Aust 2006 Feb 20;184(4):162-4 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/16489899.
  20. 20.0 20.1 20.2 Askew DA, Wilkinson D, Schluter PJ, Eckert K. Skin cancer surgery in Australia 2001-2005: the changing role of the general practitioner. Med J Aust 2007 Aug 20;187(4):210-4 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/17708722.
  21. 21.0 21.1 21.2 Youl PH, Baade PD, Janda M, Del Mar CB, Whiteman DC, Aitken JF. Diagnosing skin cancer in primary care: how do mainstream general practitioners compare with primary care skin cancer clinic doctors? Med J Aust 2007 Aug 20;187(4):215-20 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/17708723.
  22. 22.0 22.1 Wilkinson D, Bourne P, Dixon A, Kitchener S. Skin cancer medicine in primary care: towards an agenda for quality health outcomes. Med J Aust 2006 Jan 2;184(1):11-2 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/16398623.
  23. Hansen C, Wilkinson D, Hansen M, Argenziano G. How good are skin cancer clinics at melanoma detection? Number needed to treat variability across a national clinic group in Australia. J Am Acad Dermatol 2009 Oct;61(4):599-604 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/19664848.

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