Infertile??

Okay so my boyfriend has had cancer three times during his life, when he was 3, 7, and 13. He had acute lymphoblastic leukemia. He's had full-body radiation and several types of chemo. Vincristine and Methatrexate i know are low-risk. He's also been treated with Ifosfamide and Busulfan which are high-risk, meaning bigger chance of making him sterile. Both of his kidneys failed and he had a kidney transplant, he's also had a cord blood transplant, which he thinks makes his immune system pretty much new and he basically has the immune system of a 12 year old when he is really 23. We have been puzzled for a while now wether he is going to be able to have children now cause of the chemo and full-body radiation. He is going in for a sperm count but we're just worried. Any information would be helpful (: thankss.

-Marissa