Background: Since the 1990s, the imaging technique Positron Emission Tomography (PET) has been widely used. In recent years, hardly any other technology has been examined as frequently as PET diagnostics by Health Technology Assessment (HTA) Institutions. This is an expression of the uncertainty concerning the actual patient benefit of PET. Hence, there is also a lack of evidence-based reimbursement decisions or appropriate application planning of PET/PET-CT indications/devices. The aim of the present update was to identify oncological indications for which the use of PET/PET-CT is recommended or explicitly not recommended by relevant societies and in evidence-based guidelines. In the course of the update, the specific area of application (primary diagnosis, tumour grading, tumour staging/interim staging/re-staging, recurrence staging, and recurrence) for the respective oncological indication was additionally determined. The basis of the present update 2020 were two already published reports (2015 & 2018) of the Austrian Institute for Health Technology Assessment (AIHTA, formerly known as Ludwig Boltzmann Institute for HTA [LBI-HTA]).

Methods: For the identification of recommendations regarding the benefit of PET for oncological indications, a comprehensive hand search in guideline databases, websites and databases of national and supranational societies was performed. The search period was between 20.05.2020 and 19.06.2020. In addition, a search for explicitly "inappropriate" recommendations against the application of PET/PET-CT was conducted. Generally, the selection of databases and websites was based on the LBI-HTA Report 2015 and the update from 2018.

Results: A total of 37 evidence-based guidelines were identified regarding the use of PET for oncological indications. Of these, twelve recommendations were explicitly against the use of PET. In the case of four oncological indications, a positive recommendation regarding the use of PET could be identified. In contrast, for eight indications a restricted use was recommended. No evidence in favour of PET examinations was identified for six indications, and for seven indication there was no, too little or inconclusive (controversial) evidence available. The overall recommendations from the LBI-HTA report 2018 remained unchanged for 15 cancer indications. In the case of nine indications a different overall recommendations was issued and one additional disease area could be identified.

Conclusion: Just in a scarcity of instances an overall recommendations for the application of PET as a primary or standard diagnostic procedure was issued in the present update (as well as in the previous reports 2015 & 2018). Thus PET is usually part of a diagnostic chain or treatment pathway and should therefore only be used under specific obligations to prevent patient overtreatment/overuse. In general, the present summarised evidence of guidelines can support appropriate health care service provision in Austrian hospitals.