Nick Cannon and Alyssa Scott opted for their son not to have chemotherapy so he could have "the best existence he could have".
The couple tragically lost 5-month-old Zen to brain cancer in December 2021. The “Masked Singer” host explained they initially took the "active, always smiling" tot to the doctor due to concerns with his breathing and his larger-than-average head, but were stunned when he was diagnosed with high-grade glioma.
Cannon said: "They did a lot of tests. They didn't let him leave the hospital.
"And so you could imagine you think you're taking your son in to get a check-up for — at the worst, I was thinking asthma, you know? And to know that he gets diagnosed with brain cancer, that was a shock."
Cannon and Scott agreed for Zen to have a shunt drain fluid from his brain, because it wasn't an uncomfortable procedure for the baby.
He explained on “The Checkup with Dr David Agus”: "When we first went to the hospital, just to decrease his head from rapidly continuing to grow, there were a couple of procedures we were all for.
"[The shunt] to me, made logical sense. There was less pain on him and the procedure was quick. It was all about quality of life.
"From that point, they pretty much told me that best case scenario, your son could live to three or four years old. So instantly when I heard that, I thought quality of life. I wanted him to have the best existence he could have."
But when it came to chemo, Cannon asked if it would extend Zen's life or lessen his suffering and was told "not really" because of the placement of the tumour, so they declined the treatment, which the 42-year-old star himself had previously undergone as treatment for his lupus.
He said: "Seeing your son hooked up to all of those machines — and he had to go for a shunt two or three times, and that was heartbreaking every time — even in that short amount of time, I couldn't imagine him having to go through chemo.
"I knew how as a full grown man, that process ... My hair was falling out.
"I wouldn't even call it pain; it just sucked everything out of you. I couldn't imagine that on a newborn and what that would do."
In addition, the treatment would have required Zen to "live in the hospital".
Cannon said: "He would have never gone home ... [We] went to the space of 'we want to enjoy him and we want him to enjoy [us]'.“
Cannon – who has 10 other children with five other women and is expecting another baby with Scott – admitted that Zen's final days were "tough" but he and the baby's mother had some "beautiful" moment with him at the end.
He said: "I definitely couldn't have done it without her. The fact that she was the one, from every aspect she handled it.
"We had some beautiful moments. We had the opportunity, we knew the transition was coming. It happened a lot faster than we thought, but even that last weekend I knew, 'this is probably going to be the last weekend'.
"Luckily we did everything from sunrise, going to the beach, the sunset, said some beautiful prayers as a family, and really came together as a family in a very beautiful way. I'm grateful for that, but it was definitely tough. To see your child there, suffering at a point and watching things shut down, it was pretty intense."