Benefit of PET in Malignant Melanoma Assessment Questioned

The relevance of positron emission tomography (PET) alone or in combination with computed tomography (CT) in patients with malignant melanoma cannot be currently evaluated due to a lack of meaningful studies.

This is the result of a final report published by the German Institute for Quality and Efficiency in Health Care (IQWiG; Cologne, Germany) on July 20, 2011. Malignant melanoma (also known as black skin cancer) may follow very different courses. In most patients, the tumor can be removed completely by minor surgery. However, on first diagnosis some patients already have hidden metastases that are frequently 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 technique can help detect hidden metastases as early as the first diagnosis. Moreover, they hope that in follow-up examinations, PET or PET/CT can detect tumor recurrence earlier. The data obtained should then enable physicians to provide better treatment recommendations for patients.

IQWiG, therefore, searched the international scientific literature for studies investigating the impact of PET or PET/CT on health aspects directly pertinent 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.

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 imaging modality 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 two studies, so that no general conclusions can be drawn for this question either.

Studies of high methodologic quality are therefore urgently needed to examine, according to the Institute, the benefit of PET or PET/CT in patients with malignant melanoma.

IQWiG published the preliminary results in the form of a preliminary report in December 2010 and interested parties were invited to submit comments. When the comments stage ended, the preliminary report was revised and sent as a final report to the contracting agency, the Federal Joint Committee, in May 2011. The written comments were published in a separate document at the same time as the final report. The report was produced in collaboration with external experts.

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German Institute for Quality and Efficiency in Health Care