Need Advice! RadioEmbo and Resection…

My sister got news yesterday (she was diag. in early Aug; had about 5 cycles of Gem/Cis so far and recently had a CT scan). From this, they determined that the chemo has shrunk the liver tumor some, but that the tumor thrombus in the main portal vein (at the Y-shaped branch where it goes into the left and right lobes of the liver) has grown, invading both branches just at the junction. Earlier, it was mainly on the right side, (right portal vein) bulging into the main portal vein and left branch at the Y shaped split. Yesterday, there was a discussion about trying chemoembolization very soon to shrink that thrombus, with the goal still resection of right side of liver. The Dr’s conferred today and decided that was not an option; that the next step would instead be to use radioembolization on that tumor BUT…. they said that any radiation to that area would completely close the door to the possiblilty of resection forever. Very heavy words. I wonder why radioembo of a tumor thrombus in the vein would “close the door to resection”? Is it because there is not enough vein left undamaged to attach to the remaining liver segment? She has no distant mets ( not sure if this portal vein tumor is considered a met or if the one in the liver is either. No positive lymph nodes (just lymphadenopathy). They also think it has charachteristics of both hepatocellular carcinoma and cholangiocarcinoma. I found a couple posts from patients (Kris?) with perhaps “mixed” type of cancer. Radiographically, one type of cancer looks more dense and the other more diffuse. biopsy gave both as differential diagnoses. Either way, they want to try something different since the chemo is only working for the liver tumor, not the vein thrombus. Can anyone tell me why radiation might prevent ever having resection (or transplant for that matter)?