Henderson would watch videos of Genie during the treatments and said the cat's molting helped her deal with her own hair loss.
"I missed her every day I was in hospital, and my family could tell she missed me. She's my best friend and is always there when I need her," Henderson said.
"Evie was in hospital for over 300 days so we spent a lot of time in hospital and it just gave her something to look forward to when she did have those few precious days at home," he said.
The young girl was diagnosed with cancer in 2016 and said Genie would sit by her feet and "pitter-patter" on her knee to comfort her during long stays inside.
"When I've been too ill to have friends round or go outside and I've been stuck in the house, she'd come round me and that made me a lot happier and gave me great comfort," she said.
Henderson was thankful to Genie for keeping her company and was delighted the charity decided to honor her beloved pet.
"I think she's great. She deserves it. She's always been there for me," she said.