An East China boy who piled on 11 kilograms in a month to save his sick father could soon finally be jetting off on his dream holiday to Australia.

Cao Yinpeng, 8, was hailed by family and friends as a hero in the summer after he gained the weight so he could donate bone marrow to his father, Cao Lei, who was diagnosed with leukemia.

Now, the family from Xuzhou, Jiangsu province, is planning to re-book the holiday Down Under they had to cancel to cover medical bills.

Zhang Lin, the boy's mother, said the family was also forced to sell their apartment and now share a home with her parents and in-laws.

However, thanks to donations from generous well-wishers, the family is back on its feet.

More than 5,300 people have donated a total of almost 200,000 yuan ($29,500) since Cao Lei underwent a hematopoietic stem cell transplant at the Affiliated Hospital of Xuzhou Medical University on July 6.

"Many strangers visited the hospital to see us, bringing us fruit and flowers," she said. "They've given me the strength to face this difficulty. We're thankful that so many people offered to help us."

Cao Lei, 35, was diagnosed with leukemia in January, but by the time he had finished his fourth round of chemotherapy in the spring, the only suitable donor was his son. However, the child's weight was still far short of the minimum 45 kg required to safely extract the vital cells.

"It wasn't an easy decision to allow him to be a donor," Zhang said. But she knew he was her husband's only hope for survival, she added.

Doctors had said Cao Lei's parents, in their 60s, were too old to be donors, while a nationwide search by the China Marrow Donor Program found no other matches.

So, like a boxer, Cao Yinpeng began bulking up to reach the required weight.

Despite potential health risks, Zhang said the boy stuffed himself at every mealtime, and that she encouraged him by making all kinds of dishes, telling him, "You need to have more to save your father."

He also spent more time exercising to build his strength. Every night, he would walk for at least an hour around his residential community.

By mid-June, Cao Yinpeng had gained 11 kg, which meant doctors could begin preparation work for a transplant. Nurses extracted 700 to 800 millimeters of blood every week in the run-up to the operation, leaving the boy sluggish and pale, Zhang said.

"The father is recovering well so far," said Sang Wei, one of the doctors treating Cao Lei. He added: "The boy impressed medical workers a lot with his optimism."