The diagnosis was made after the 31-year-old return abnormal blood tests during a routine pre-season check-up.
Treatment has already begun and former Aston Villa midfielder Petrov made a trip to see the Nigerian international.
Petrov himself successfully battled Leukaemia after being diagnosed in 2012.
The Bulgarian told the Birmingham mail: "I went to see Carl the other day, so we had a little chat. Obviously there were a lot of questions in his mind, and he was in very good spirits."
"He's started his treatment now. It's a long road to follow. He had so many questions so I've been through it with him."
"You need to answer in a way that's going to give him everything that will happen, what to expect, how to deal with it, what are the side-effects, how he's going to approach everything."
Petrov was under no illusions that the battle would be an easy one, but said that Ikeme could count on the support of people from all over the world.
"There's a lot of things, but he's in good spirits and that's the main thing. I said to him, 'You'll have great support. Everybody around the world will support you and it's a great help,'" Petrov explained.
"It's a long road, it's hard, it's tough, you need to really battle through it."
"But look at me now. I'm alive, I'm kicking. It's life afterwards and it's worth it when you battle so hard to appreciate life even more afterwards."
Everyone at BeSoccer wishes Carl a full and speedy recovery.