Benefit of PET in malignant melanoma is unclear

This is the result of a final report published by the German Institute for Quality and Efficiency in Health Care (IQWiG) on 20 July 2011.

Hidden metastases are often detected too late

Malignant melanoma ("black skin cancer") may follow very different courses. In most patients the tumour can be removed completely by minor surgery. However, on first diagnosis some patients already have hidden metastases that are often detected only at a later stage. Many health care experts hope that an examination with PET or PET/CT, alone or in combination with other methods, can help detect hidden metastases as early as the first diagnosis. In addition, they hope that in follow-up examinations, PET or PET/CT can detect tumour recurrence earlier. The information obtained should then enable doctors to provide better treatment recommendations for patients.

Benefit for patients is crucial

IQWiG therefore searched the international scientific literature for studies investigating the impact of PET or PET/CT on health aspects directly relevant to patients. For example, the test results could help treat patients with further useful therapies at an earlier stage, or the results could help spare patients unnecessary treatment. However, the search for such studies was unsuccessful, so that the question as to the benefit of PET or PET/CT remained unanswered.

Reliability not clear

In addition, IQWiG searched for studies in which the diagnostic accuracy of PET or PET/CT was compared to other test methods. This investigates the question as to how often a PET test produces wrong results. The test should on the one hand overlook metastases as rarely as possible, but on the other, should not raise unjustified suspicions. Although a total of 17 diagnosis accuracy studies were found, the diagnostic accuracy of PET or PET/CT varied greatly in these studies. A comparison of PET or PET/CT with other technologies (e.g. CT alone) was investigated in only 2 studies, so that no general conclusions can be drawn for this question either.

Studies of high methodological quality are therefore urgently needed to investigate the benefit of PET or PET/CT in patients with malignant melanoma.

An overview of the background, methods and further results of the final report is provided in the following executive summary.