The Wallaby back was diagnosed in August 2016, but revealed he was in remission in February this year after a bone-marrow transplant.
The Brumbies will play the Hurricanes in Friday's quarter-final, having topped the Australian Conference, but it is without a win against New Zealand opposition since a 52-10 victory over the Wellington club at the very start of last season.
With the odds stacked against him, coach Stephen Larkham does not view Lealiifano's possible return in Canberra as a risk, with a previous comeback delayed by a hamstring strain.
"It would be a gamble if I thought he wasn't right to play so we'll wait and make that assessment after we see how he trains," Larkham said.
"We'll name the team Tuesday but the way he's trained within the team over the last three months gives me a fair indication that he's ready to play."