Commentary: Start with the KISS principleBMJ 1998; 316 doi: https://doi.org/10.1136/bmj.316.7124.38 (Published 03 January 1998) Cite this as: BMJ 1998;316:38
- Rod Sinclair, senior lecturera
- a Department of Medicine (Dermatology), St Vincent's Hospital Melcourne, Fitzroy, Victoria 3065, Australia
The article by Jackson et al asks the question whether a self reported questionnaire can enable selective screening or primary prevention of melanoma to be more precisely targeted towards groups at risk and thereby enhanced. To answer these questions it is important to define the issues and to deal with aspects of primary prevention and secondary prevention (or selective screening) separately.
Primary prevention strategies attempt to reduce or limit exposure to carcinogens so as to prevent or slow down cancer.1 The criteria for effective primary prevention consist of recognisable risk factors, modifiable risk factors, and a demonstrated need for a primary prevention campaign.
In the case of melanoma there are constitutional risk factors about which little can be done, such as skin type, response to sunlight, and the tendency to freckle and develop moles on exposure to sunlight. Exposure to sunlight, however, particularly in large episodic doses during childhood, is a behavioural component that is amenable to change. The success that the sun smart campaign in Australia has had in modifying the attitudes and behaviour of young Australians confirms this.2
Whether or not this change is worth while in the United Kingdom will depend on the incidence and impact of melanoma in the community. The designation of prevention of skin cancer as a Health of the Nation objective shows that such activities are perceived as worth while. The consequences of such change include a shift in cultural norms, and there is a risk of discouraging children from otherwise healthy outdoor summer sporting activities such as cricket and swimming.
The potential benefits of such a primary prevention campaign on diseases other than melanoma also needs to be considered. These benefits include reduction in non-melanoma skin cancer and premalignant keratoses, which currently place a considerable burden on the NHS, and reduced photoageing and wrinkling of the skin.
The suggestion that primary prevention programmes could be enhanced by targeting high risk groups requires careful consideration and further validation. In the Australian experience, the necessary increased complexity required to convey a message to a target group tended to diminish the message. Care would need to be taken to ensure that advice to “stay out of the midday sun” and “slip on a shirt, slap on a hat, and slop on some sunscreen—especially if you have a lot of moles, freckles, atypical moles, or previous sunburns” is not interpreted by those not belonging to this target group as carte blanche to go unprotected into the midday sun. This is important, as the designated target group excludes at least 10% of people at risk of melanoma and an even greater percentage of people at risk for non-melanoma skin cancer.
Secondary prevention strategies attempt to detect cancer or it precursors while its capacity for metastasis is low and it can still be cured by local treatment. Secondary prevention tactics include educating people to recognise warning signs and to seek early medical attention, case finding, and population based screening programmes which aim to identify previously undetected malanomas.3
One strategy for early diagnosis involves educating the public to recognise suspicious signs and see the doctor early and educating primary care practitioners and specialists to appropriate lesions for biopsy. Mackie has shown that recognition of melanoma can be improved and that this leads to an increase in the number of patients presenting with thin melanoma.4
An additional strategy involves case finding, where primary care physicians are asked to routinely examine patients' skin for melanoma when they present for unrelated matters. Currently more than a fifth of melanomas are first detected by a doctor, before the patient has noticed anything wrong, and such a strategy has the potential to increase that number.
A third method of secondary prevention is population screening (box). Screening for melanoma involves an examination of the entire skin surface (excluding the genital area) and takes 5-10 minutes. The cost is of the consultation fee for the physician. It is free of major discomfort and side effects but is inconvenient.
Effective population based screening
Safe and effective
Acceptable to the general public
Highly sensitive and specific
Increased workload with consequent disruption to routine services
Potential problems with population based screening for melanoma are that the sensitivity and specificity have not been quantified and the cost is substantial. Population-wide screening is not recommended by the International Union Against Cancer and is not being advocated in Australia, mainly because the performance and validity of the test procedure is unknown.
Screening of self selected people at high risk, as advocated by Jackson et al, has considerable appeal, but before the current protocol is accepted more information is required on several aspects. The value of the test procedure is not known, and in particular general practitioners' ability to detect melanoma has not been measured. If nurses were to do the examination, their expertise would require validation. Some general practitioners have difficulty doing skin examinations, and some well trained nurses could be expected to have similar difficulties.
Secondly, more information is needed on the cost of the procedure. The Jackson protocol involves inviting the entire British population to fill in a questionnaire, contacting the 30 or so million who fail to respond, and then examining 8.7% of those in the high risk groups—5-6 million people. The cost would be substantial and should to be compared with the potential savings that would be achieved by early detection of melanoma.
It is also not known whether advice to “watch your moles for change in size, shape, or colour if you have lots of moles, freckles, atypical moles, or previous sunburns” does not inadvertently tell people that they need not watch moles for change in size, shape or colour if they don't have “lots of moles, freckles, atypical moles, or previous sunburns.”
Until these issues are resolved, public education programmes would be wise follow the Australian model and adopt the KISS principle: keep it simple, stupid.