Published in the Green Journal, this survey study reported findings of the current practice of proton therapy for adult cancers in Europe. 19 out of 22 centers from all 13 countries where PT is available, participated in the survey. 4233 adult patients are currently treated across Europe annually, of which 46% consists of patients with central nervous system tumours (CNS), 15% head and neck cancer (HNC), 15% prostate, 9% breast, 5% lung, 5% gastrointestinal, 4% lymphoma, 0.3% gynaecological cancers. CNS are treated in all participating centres (n=19) using PT, HNC in 16 centres, lymphoma in 10 centres, gastrointestinal in 10 centres, breast in 7 centres, prostate in 6 centres, lung in 6 centres, and gynaecological cancers in 3 centres. Reimbursement is provided by national health care systems for the majority of commonly treated tumour sites. Approximately 74% of centres enroll patients for prospective data registration programs. Lack of evidence for PT and reimbursement issues are the most reported reasons for not treating specific tumour types with PT.