DISCUSSION Metastatic lesions to the pancreas are uncommon, and account for less than 2% of all pancreatic malignancies. The tumors that metastasize most frequently to the pan- creas are renal cell carcinoma, melanomas, sarcoma, and colon, lung, and breast cancer [1,2,6]. Although pancreatic metastasis is rare, high volume centers will encounter pa- tients with resectable metastatic disease. Reddy et al. [7] reported on 49 patients that underwent pancreatic re- section for metastases from 1970 to 2007, which is the larg- est single institutional series on pancreatic resection for metastatic nonpancreatic cancers. At our center, 11 (0.7%) of 1,571 pancreatic resections were performed for meta- static tumors of the pancreas, which appears to be low compared with other series [1,2,5,8]. The symptoms of pancreatic metastases are frequently non-specific and sub- tle, therefore pancreatic metastases are often found during regular surveillance imaging for primary cancers. Reddy et al. [7] reported that 45 of 49 patients (92%) had symp- toms of abdominal pain, jaundice, weight loss, whereas another study reported that 6 of 13 patients (46%) were asymptomatic [2]. In our series, 9 of 11 patients (82%) were asymptomatic. The preoperative differential diagnosis between a pri- mary pancreatic neoplasm and a metastatic tumor may be problematic. Palmowski et al. [9] showed that unlike pan- creatic adenocarcinoma, secondary pancreatic cancers usually show arterial phase enhancement on contrast- en- hanced CT scans. Furthermore, unlike pancreatic adeno- carcinoma, metastatic pancreatic lesions from RCC, color- ectal cancer, and breast cancer tend to be rim-enhanced. In the present study, 9 metastatic lesions from 7 RCC and 2 carcinoid tumor were rim-enhanced or heterogeneously enhanced, whereas the other 2 lesions from rectal cancer and leiomyosarcoma were not. Furthermore, in order to avoid major surgery, accurate preoperative staging must be done in patients with widespread disease [3,4,10,11], and 18-FDG-PET has proven to be useful in this context [5,12]. Our patient with a metastatic carcinoid tumor in the mediastinum and pancreas was found to have two other lesions by 18-FDG-PET, which were not detected by CT, but which were finally confirmed by endoscopic ultra- thesurgery.or.kr Surgical resection of metastasis to the pancreas sonography. Percutaneous and endoscopic fine-needle bi- opsies may help establish a pathological diagnosis when a metastatic tumor is not amenable to surgery, but may be treated with chemotherapy. The time between diagnosis of primary cancer and the detection of pancreatic metastasis varies widely, and in particular, renal cell cancers are associated with a pro- longed disease-free interval [4,6,13]. In the present study, the median time between primary disease and metastasis diagnoses for the renal cell cancer patients was 64 months (range, 14 to 180 months), and for the other patients was 50.5 months (range, 14 to 180 months). Surgical resection of metastatic tumors to the pancreas should be approached by carefully applying appropriate selection criteria, because of the substantial morbidity as- sociated with pancreatic resection and the questionable benefit of resection for pancreatic metastasis. Reddy and Wolfgang [14] in a systemic review of the literature, eval- uated 243 patients who had undergone radical pancreatic resection for metastatic disease, and concluded that the ef- fectiveness of pancreatic resection for metastatic tumor is dependent on the tumor biology of the primary cancer. RCC was found to be associated with best outcome, whereas lung cancer predicted the worst. Of their 243 pa- tients, 193 (80%) had RCC, 19 colon cancer, 12 melanoma, and 12 sarcoma: median survivals and 5-year survival rates of patients with metastatic RCC were 8.75 years and 66%; those of patients with metastatic colorectal cancer were 54 months and 27%; those of patients with metastatic sarcoma 40 months and 14% and median survival of pa- tients with metastatic melanoma 14 months. We could not estimate 5-year survival in our cohort because there were only 11 patients. Reddy and Wolfgang [14] also suggested criteria for patient selection, namely, a primary cancer type associated with a good outcome, control at the primary cancer site, isolated metastases, resectability of metastasis, and the patient’s ability to tolerate pancreatic resection. Though 2 patients with RCC and one patient with carci- noid had a extrapancreatic disease in the present study, metastasectomy was performed and these 3 patients were alive at the end of the study. It is difficult to conclude that surgical resection of multiple metastasis will provide sur- vival benefit. It may be reasonable to follow the treatment 281