Janice St Fort, who stood by the footballer's side through the turmoil of losing his wife Rebecca, died at the London Bridge Hospital at the age of 58 after losing her battle to the disease with her family at her bedside on Thursday.
The family of Rio issued a statement announcing the tragic news of the death of their mother.
The statement read: 'We are heartbroken to announce that our amazing mum Janice passed away today after an ongoing battle with cancer,'
'She was an inspiration to us all and was loved by everyone who knew her. She died at Guy's Cancer Unit, London Bridge Hospital, with her loving husband Peter and us, re, at her bedside.
'She was a devoted mother to us all, and she was the most incredible grandmother to our children.
'The whole family are devastated.
'Our mum was the centre and the heart of our family and has supported us all through many difficult times, always with a smile on her face.
'Her strength and courage, as well as her great sense of humour and immense kindness, were never-ending.
'We would like to thank all the staff at Guy's Cancer Unit for looking after our mum so well during her illness especially Marta and Joanna as well as everyone who has sent kind wishes to us all during this difficult time.'