Bill Gould said his daughter's cancer specialist offered some words of wisdom when Natasha was diagnosed with diffuse intrinsic pontine glioma (DIPG) cancer in May of 2015.

"When she was diagnosed the first words that the oncologist said to us was, 'I am so, so sorry for you and your family and for Natasha.' He also said 'Have a summer of a lifetime,' " Gould told CBC News Saturday.

Calgary father talks about his daughter's brain tumour diagnosis0:41

"And so that's what we aimed to do, to have a summer of a lifetime, it turned into having a year of a lifetime. We packed in a lot of things. There was no regrets."

Natasha Gould, 12, passed away Thursday from an aggressive inoperable brain tumour.

In the last 15 months of her life, she found a passion in advocating for more research in childhood cancers.

"She saw that she had a purpose in her life to advocate and spread the message and draw attention to the fact that we need more energy to try to find a cure to childhood cancers and I want to continue that momentum on her behalf," her father said.

He said his family's work, continuing Natasha's mission, will be a challenging one.

More collaboration, cooperation

"There is not an easy solution to all of this, certainly more research funds need to be dedicated to childhood cancers. I also believe there needs to be more collaboration and cooperation amongst various researchers," Gould said.

"I think there needs to be a greater openness between our traditional, western, scientific approach to medicine perhaps being more inclusive to some alternative and natural medicines. There are a variety of things that need to be done."

Gould is not alone.

John Feradi lost his son Jordan at the age of eight to the same disease about four-and-a-half years ago.

"The worst form of cancer a child can get," Feradi said, describing DIPG cancer.

"No known cures, average median survival is eight to 12 months."

Jordan died eight months after being diagnosed.

"I was very disappointed in the lack of research or any strides made, there hadn't been any advances in 40 years since radiation. It is a difficult thing being told there is nothing we can do," Feradi said.

John Feradi

John Feradi lost his son Jordan at the age of eight about four-and-a-half years ago, so he started a foundation to improve research funding for childhood cancers. (Julien Lecacheur/CBC)

That prompted him to take action. He started the Canadian Children's Brain Cancer Foundation to push for more action on childhood cancers.

"I believe in medical science," he said.

"I think if we can give the research community the resources that they need I honestly think we can find some clues or at least improve the treatment for diseases like this because the treatment sometimes is worse than the disease itself."

Bill Gould said in the last few months of Natasha's life, she found her voice.

"We are a family of faith and we draw on energy knowing that God gives us strength," Gould said.

"She talked about the need to serve others. She didn't want money to be raised just for DIPG cancer, she wanted money to be raised for all kids with cancer."

Natasha Gould

Natasha Gould was interviewed by several major media outlets in the U.S. after an event she was participating in near the White House was shutdown by the Secret Service. (Brian Burnett/CBC)

During a trip to Washington, D.C., last fall to take part in a candlelight vigil for cancer research funding, Gould spoke out in interviews with several American media outlets after Secret Service officers shut down the event over security concerns.

His daughter's passing has left the family with a long-term project.

"We will learn how to live this new normal for us without Natasha. We will strive to have the strongest relationships that we can and continue to make her dreams come true on her behalf," he explained.

"In the moments after Natasha passed here in this house … we talked about the great amount of support, financial support, just people being here, people dropping off food, support through prayer. We were wondering, 'How do we pay this forward somehow?'" Gould asked.

"It is a question that we have that has not been answered for us yet, but we know that we will find a way."

With files from CBC's Julien Lecacheur