I definitely recommend a second or third opinion. We had to work through our insurance (HMO) to see where they contract with and then who our physicians group contracts with because apparently they can further reduce your options. The best bet is to talk to your doctor (we worked with our oncologist to get referrals to different surgeons) and they can work with your insurance and put in the referrals. I was told that in California HMOs limit you to in-state. Not sure if that is completely true or not though.
We also self referred ourselves to one doctor and will have to pay for that consultation out of pocket since they don't contract with our insurance/physicians group.
We saw Dr. Imagawa at UC Ivine, Dr. Selby at USC, and Dr. Colquhoun at Cedars Sinai in Los Angeles. All three had differing opinions as to the plan. My husband's tumor also was too large and close to major veins to do surgery initially and Dr. I recommended chemo to shrink it. We did that for two months and then rescanned. At the next appointment, same story. That's when we went for the second and third opinion.
Dr. Selby said to do surgery now. We couldn't get the insurance thing worked out and he recommended Dr. C. We met with Dr. C and discussed the other two opinions and he recommended a portal vein embolization procedure and continue chemo to prepare him hopefully for a trisegmentectomy. One thing that helped us visualize it was having the doctor explain the scan images and show us where the tumor was and also explain how the resection surgery is done. The doctor showed us what segments they would take out of my husband. He had the PVE procedure done in January and we are waiting for a rescanthis month to see if surgery will be an option.
So long story short, it seems each doctor has different approaches and opinions. It's definitely worth seeing others to ether confirm the path you are on now or see if there are other options. Also, it seems that each case is different because of the location of the tumors and proximity to the portal vein and Inferior Vena Cava, but there are cases that shrinking the tumor will lead ultimately to resection. Porter on this board is a recent example of shrinking her tumor and then having a resection (and I'm hoping my husband will be one too!)
Good luck and take care.