Extended surgery is being widely performed to treat pancreatic cancer in Japan, but it has not been evaluated in the same way as in other countries. We, therefore, compared the Japanese Stage Classification (JPN-SC) with the Union Internationale Contre le Cancer Stage Classification (UICC-SC) in the surgical cases of pancreatic cancer treated in our department and then assessed the results of extended resection and associated problems. Problems existed in the resection rates and actuarial survival rates in stages II and III in the UICC-SC, and the JPN-SC was found to reflect more accurately the outcome. On the other hand, although improvements in curative resection and actuarial survival rate have been achieved as a result of extended resection in Japan, the outcome in JPN-SC surgical stage IVb and highly advanced cases in which these resections proved to be noncurative even though they were classified as surgical stage IVa was extremely poor. In the future, it will be necessary to decide on a single-stage classification that is accepted throughout the world and to conduct prospective studies matched to the degree of tumor progression.