Malignant melanoma, which can be fatal, is increasingly common and there is debate about whether it should join the list of cancers that are screened for. A new Cochrane Review from June 2019 looks at the current evidence and we asked one of the authors, Minna Johansson from Cochrane Sweden, to tell us what they found.
In thinking about screening for cancers such as malignant melanoma, it’s important to remember that the vast majority of screened people cannot benefit from the screening because they will never develop the disease. When healthcare systems invite asymptomatic people to a screening intervention that they have not asked for, it leads to ethical considerations that differ from those in regular health care; we need to know that we do not cause more harm than good - and requirements for the certainty of the evidence are even greater than usual.
At the moment, Germany is the only country in the world with a national screening programme to detect malignant melanoma, but in many other countries, opportunistic screening is widespread. We wanted to find out whether screening is effective at reducing the adverse health impacts of melanoma and whether it has any harms.
Screening has the potential to reduce deaths from melanoma through earlier detection but potential harms could arise if people without symptoms are found to have melanomas and other skin lesions that would never have caused problems if they had remained undetected. They may then receive unnecessary surgery, or experience psychological stress. There is also a risk that financial and human resources used for screening could be better used on other interventions with a stronger evidence base and a better balance between benefits and harms.
We reviewed the evidence for the benefits and harms of organised screening for malignant melanoma compared with no screening. We looked for all types of screening, including skin self‐examination or examination by a health professional, of any person not suspected of having malignant melanoma. We included people thought to have a high risk of developing malignant melanoma but not those known to previously have had melanoma.
We found two randomised trials that met our inclusion criteria, but neither reported data on the important outcomes we wanted to investigate. This leaves us with insufficient evidence to quantify the benefits and harms of screening for malignant melanoma, and means that current screening practices for melanoma do not live up to the required evidence standards of organisations such as the WHO and the UK National Screening Committee, which specifically highlight the importance of solid evidence for both benefits and harms prior to implementation of a screening programme.
In summary, our review shows that adult general population screening for malignant melanoma is not supported or refuted by evidence from randomised trials and therefore does not fulfil well-established screening criteria. Yet screening for malignant melanoma is currently practised in many countries in a more or less organised form. A robust randomised trial is highly desirable to enable people to weigh potential harms against potential benefits, both to make sure that a screening programme will not cause more harm than good and to ensure that, if it does have important potential benefits, it is not dismissed inappropriately.