1 National Center of Oncological Hadrontherapy (Fondazione CNAO), Pavia, Italy.
2 National Center of Oncological Hadrontherapy (Fondazione CNAO), Pavia, Italy. Electronic address: vitolo@cnao.it.
3 General Surgery Department, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy.