Wilms tumour, a cancer of the kidneys, occurs mostly in children.
Riays had nine weeks of chemotherapy in Christchurch in a failed effort to shrink the tumours. In November she was moved to the Starship children's hospital in Auckland where her kidneys were removed.
The clinical director of the Starship renal service, Dr William Wong, said: "Riays' condition is very rare in the fact that both her kidneys had tumours and both kidneys had to be removed."
More chemotherapy followed the surgery to eradicate any remaining cancer cells, and she must have 12 hours of peritoneal dialysis each day to do the blood filtering and waste removal work normally done by the kidneys.
Miss Turitanga said Riays frequently catches colds because the chemotherapy suppresses her immune system, but she is otherwise healthy. The three-weekly therapy, however, makes her vomit a lot and she lost some of the small amount of baby hair that she had grown.
"She has good weeks and she has bad weeks."
Miss Turitanga said either she or her partner, Sam Taulupo'o, would donate a kidney to their daughter once she was approved for a transplant, although neither of them had been checked for compatibility yet.
The couple have two older daughters, Trinity, 9, and Jaydis, 5, and a fourth child is on the way.
Miss Turitanga plans to have the baby - which is due in March - in Auckland. She and the two older girls are staying at the Ronald McDonald House near Starship and Mr Taulupo'o, who works for a paint manufacturer, visits from Wellington once a fortnight.
Miss Turitanga said one of the highlights on the ward in Starship is the weekly delivery of fresh fruit for patients and their families by New World.
Riays - who is fed a special formula through a nose tube to her stomach - just fiddled with a grape when the Herald visited, but her sisters could hardly wait to tuck into the fruit. The supermarket group began the deliveries of fruit to the parent rooms on seven wards last July.
Wilms tumour
• Cancer of the kidneys.
• Occurs in around one in 10,000 children aged 1 to 5.
• Affects both kidneys in only 5 per cent of cases.