The goal of this clinical trial is to evaluate the safety and efficacy of neoadjuvant capecitabine and cyclophosphamide treatment in patients affected by huge Pseudomyxoma peritonei (PMP) (peritoneal cancer index \>28). Treatment consists of metronomic (low-dose medication for a prolonged time) of capecitabine plus cyclophosphamide for 6 months followed by standard of care cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). The main question the trial aims to answer is which is the proportion of patients with complete cytoreduction at CRS/HIPEC after neoadjuvant metronomic approach with oral capecitabine and cyclophosphamide in patients affected by huge PMP.