The star, who was first diagnosed with the disease in 2009, passed away at a hospital in Glasgow, Scotland on Saturday (26Jan13), just days after she was admitted to the health facility.
Fitz-Simons was most famous for her role in soap opera Take the High Road, and her former co-star Gary Hollywood, who played her adopted son Dominic in the drama, has paid tribute to the actress.
He tells Scotland's Daily Record newspaper, ""I'm devastated. She really took me under her wing on Take the High Road. I was only 14 at the time and she'd only been 14 when she started acting so she understood what it was like for me early on in my career.
""She is my eldest son Zach's godmother and he is 13 now. We were very, very close and she taught me greatly. She was a real star and my heart goes out to her family after hearing this awful news.""