Proton therapy is a radiation therapy technique which allows large doses of radiation to be delivered to cancerous tumours without (excessively) “overflowing” to adjacent tissues. There has been much talk of this technique in recent years, since two projects by proton therapy centres are ongoing in Belgium, one in Louvain and the other in Charleroi. This treatment is used each year on about fifty Belgian patients, most often children affected by rare cancers who are sent to specialised centres abroad and fully reimbursed by INAMI. Before considering expanding the reimbursement of this extremely costly technique to include other types of cancers, INAMI asked us to verify the merit of its use. However, after an in-depth analysis of the international scientific literature, we were unfortunately unable to find compelling evidence of the superiority of the technique in comparison to conventional radiation therapy.