A family is asking for people across the globe to help support a boy with cancer.

Malcolm McGregor, 4, learned on Dec. 24 he has cancer, his family said. He has already begun undergoing chemotherapy treatment. “We’ve only been home four days since Christmas Eve,” his mom, Tracy McGregor, said Sunday. Malcolm has neuroblastoma. It forms in immature nerve tissue, often in early childhood, according to the National Cancer Institute.

A superheroes fan, he named his tumor Shredder, the Teenage Mutant Ninja Turtles' archnemesis, the Wisconsin Rapids Tribune reported. When he’s asked who his favorite superhero is, he responds, “All of them.” His mom said he likes any of them that are blue.

On Wednesday the family said it’s looking for cards and letters from people all over the world. People from about five states have already sent their support, and they often call Malcolm their superhero.

Tracy McGregor said he doesn’t quite understand the severity of it, but he thinks it’s cool that people are thinking about him.

Cards can be sent to the following address:

Malcolm McGregor  P.O. Box 322  Wisconsin Rapids, WI 54495-0322