In their paper Murchie et al pose the question of whether it matters if the excision of primary cutaneous melanoma is performed in primary care by GPs.1 We refute the conclusion that this is a way to expedite diagnosis or that it should lead to a change in guidelines. Their results should not be seen as providing commissioners with alternatives to referring all suspected melanomas for specialist assessment as recommended in current guidelines from National Institute of Health and Clinical Excellence and British Association of Dermatologists/British Association of Plastic Reconstructive and Aesthetic Surgeons updated last year.2,3 Eight out of 11 studies of skin cancer excisions showed that clearance is more adequately achieved by dermatologists/specialists.
The data from 1991–2006 predate guidelines and modern skin cancer services with 21% being excised by general surgeons and only 15% by dermatologists. This is not generalisable to the rest of the UK or to our current practice. From the same population we have audit data from 2009 that reflect a change in practice with the introduction of a modern skin cancer service based on national guidelines. This has reduced waiting times with a reduction in primary care excisions and increased roles for dermatologists. There were a total of 130 melanomas in Grampian, Scotland, in 2009. Dermatologists diagnosed 60 (46%), 43 (33%) by plastic surgeons, 22 (17%) by primary care, and 5 (4%) from other sources. Of the 22 melanomas excised in primary care, 16/18 were complete excisions. The remaining four melanoma specimens were incised, shaved, or curetted, in other words, incompletely excised. Dermatologists and plastic surgeons had complete excision rates of 84% and 89% respectively, excluding incision biopsies.
Of the 22 melanomas coming from primary care, none had a possible diagnosis of melanoma on the request form, delaying pathological diagnosis, impeding clinico-pathological correlation, and correct diagnosis. Dermatologists expected melanoma in 54/60 and plastic surgeons in 29/43.
Modern dermatological diagnosis of melanoma assisted by dermoscopy has a high sensitivity of 0.88 and specificity of 0.86.4 In Murchie et als' study the correct diagnosis was only given in 19.5% of melanomas diagnosed in primary care.
If services are provided by practitioners who are poor on diagnosis, irrespective of surgical competence, then unnecessary excisions will waste resources, and the risk of melanoma being missed is increased. The authors' assertion that if excision is complete then ‘differences in diagnostic skill do not matter’ is at least shortsighted or intended to provoke controversy.
- © British Journal of General Practice, April 2011
