David Foster's Daughter Amy Opens Up About Breast Cancer Battle and 'Being Strong' for Her Kids

Amy S. Foster — the daughter of hit record producer David Foster — has found strength in those closest to her throughout her breast cancer battle.

The author and songwriter, 46, who appears in the new documentary David Foster: Off the Record about her father's life and career, tells PEOPLE that her family and three kids have helped her to not be "afraid" after she was diagnosed with breast cancer last year and underwent a mastectomy.

"I have young kids, and I think you end up being strong for them," Amy says. "In the course of being strong for them, you automatically become strong. The mastectomy was not great, but it never was a question for me. I was just like, 'Take them.'"

With the ongoing coronavirus pandemic, Amy says she's been taking "extra precautions" to maintain her health.

"I am on chemotherapy every day," she says. "I'm on a pill form of chemo which makes my immune system not as strong. It's only been a year since I was diagnosed and had my mastectomy, and I have to have another revision surgery. So I can't really be out."

In David Foster: Off the Record, Amy candidly opens up about her relationship with her father, which she says has evolved throughout the years. Now, she says, "He understands that as a parent, it's a lot more than providing — he puts time in, he puts energy, he puts effort."

A specific example Amy cites is how David, 70, and his wife of one-year Katharine McPhee, 36, flew out to Portland — where she lives with her family — to stay with her when she had her mastectomy.

"[Our relationship] has grown a lot, and I think my dad and I are a lot alike," she says. "The relationship that I have with my dad is so great now. He's not so stuck in his ways that he thinks that he's intractable, that he doesn't need to change. He's evolving every day, and I love that."

Amy and David Foster

It has taken a while for them to get to this place, though, as Amy admits growing up in a separate home from her father was sometimes "challenging." She grew up in Toronto with her mom, David's ex-wife B.J. Cook, while her father lived in Malibu.

"My dad was so young when he had me, I want to say 23," she says. "Dads in the '70s did not operate the way that dads operate now. He really did believe that his job was just to provide."

But still, she says, "I would not have had it any other way because I'm really grateful that I grew up where I grew up."

"I did not grow up entitled, I did not grow up with money and I really had to work for everything," she says. "I think that shaped my character in a way that gave me a lot of resilience, which you need in life and certainly in the writing entertainment profession."

RELATED: Amy S. Foster Diagnosed with Breast Cancer: 'The Great News Is That I Caught It Early'

For Amy, watching David Foster: Off the Record was "both triggering and healing."

"I was really taken back to those moments of my childhood that were painful, and I saw that girl who was me and I felt so much empathy for her," she says. "I wished that I could go through the movie screen and whisper in her ear and tell her, 'It's going to be fine.'"

Amy says she'll always be proud to be a Foster along with her sisters Allison, 50, Sara, 39, Erin, 37, and Jordan, 34 (from David's previous relationships).

"If you look at other higher profile families, our situation is very rare [in] that none of us are troubled," she says. "I think it's because we're just all very grounded. We felt responsible to each other so that kept us out of trouble. We wanted the Foster name to have a positive connotation."

RELATED: David Foster and His Daughters on Difficult Past and Life Now: 'We've Worked Hard to Get Here'

Chad Buchanan/Getty Amy and David Foster

In quarantine, Amy has continued to write and hopes David Foster: Off the Record will show a different side to her father.

"My father's journey is so interesting, and I hope that people don't judge him based on how many times he's been married," she says. "I really hope that people understand that this singular talent that my father has is one that if given to somebody else, they might not have become David Foster. That the talent was one component but his dedication and his hard work and his focus is what made him David Foster."

"It wasn't like he had it easy," she continues. "He worked for everything, every inch of ground that he got. I think that that is something that he passed down to us."

David Foster: Off the Record is streaming on Netflix now.