Your surgeon is likely opting for surgery first due to the tumor impacting the bile and pancreatic ducts. In my case the tumor was thought to be very close to my portal vein and conventional wisdom was to prevent the tumor from further impacting critical structures and becoming inoperable. There is no guarantee the chemo regimen used (generally Folfirinox) for curative intent will be therapeutic. If it is not and the tumor progresses, then the opportunity to perform surgery is lost and it comes down to trying another chemotherapy regimen and doing aggressive chemotherapy. Presently there are only thee, first-line regimens.