While it is high risk, we were told there is a "screen" that can be placed in the VenaCava to catch the thrombus if it detaches. It prevents it from moving to the heart. Ask your doc about that. Fortunately for us, the growth was wrapped around the outside and not actually in the the IVC.
I don't know where you are being treated, but we were sent to UCLA in CA, which is close to us. The surgeons there were phenomenal.
Hope this helps some,
Wynette