Ovary. Any tumor that spreads to the peritoneum can cause ascites. Of the common tumors ovarian cancers have a greater tendency to invade the peritoneum and cause ascites. Mesotheliomas are primary tumors of the peritoneum and cause ascites, but are not common. Some tumors cause ascites by blocking the lymph vessels, e.g. Stomach and pancreas cancers. Liver cancers may be associated with ascites.