When distal pancreatectomy is carried out for left-sided pancreatic cancer, splenectomy is usually performed not only for margin-negative resection but also for effective clearance of the splenic hilar lymph nodes. However, there was no scientific evidence regarding the justifiability for spleen resection. Considering potential immunological function of the spleen, the investigators hypothesized that distal pancreatectomy without pancreatectomy for left-sided pancreatic cancer is superior than Distal pancreatectomy with pancreatectomy in terms of short-term perioperative outcomes and disease-specific overall survival.