"The MRI came back and the tumour is gone.
"That was just the best news for all of us. Everything is looking promising," she said.
"But Sophie had to learn to walk again this year and her immune system is still pretty shot after all the treatment she had to undergo," Ms King said.
"She really deserves a holiday when she's ready and I want to help make that happen for her."
Ms King was among those selected to attend the birthday bash for Prince Charles at Government House on Wednesday.
Eketahuna woman Maureen TeWake, who took her friend Helen Thomas, and Masterton farmer Ross McLachlan were also selected from more than 1500 applicants who shared the prince's birthday.
Each guest was given a cake, and Ms King, who is based in Palmerston North, has listed hers on auction site Trade Me.
The cake comes with a decorative paua and leaf garnish and a carry box branded with a royal seal. The auction had reached $75 as at noon yesterday .
Two other cakes from the royal party also are up for auction on the site - a slice of the fruit cake and another boxed guest's cake. A slice of the prince's fruit cake sold on the auction site on Friday for $555.
To bid for the cake go to Trade Me.co.nz and enter Prince Charles Birthday Cake For Charity in the search box.