Two years ago Susan DeWitt was diagnosed with lung cancer. It has been an incredibly painful struggle for the Denver mother of three -- and even more difficult for her children to watch.
DeWitt's son, Cody, will not forget the day he learned of his mother's cancer -- or any day since then. He and his 14-year-old sister, Gabrielle, have documented their family's struggle on videotape.
"I was crushed when I first learned the news," said Cody on the homemade documentary.
They originally hoped the tape would get people to quit smoking but now recognize it is doing even more. It's helping other teens cope.
"A lot of times teenagers don't know who they can talk to, and then they don't know how to talk about it," said Cody.
Studies show that one out of every four adults diagnosed with cancer has young children or teenagers. More than 200,000 children learn the news every year.
"No one should have to think about losing their mother," said DeWitt, "particularly in this way."
When Dr. Wendy Harpham's cancer went into remission, her 4-year-old daughter had a question: "Mom, now that it's gone, can it come back?" said Harpham.
"As a patient, I wanted to say, 'No, we don't have to worry about cancer anymore.' When my cancer did come back for the first time, I was so glad I'd been truthful with my daughter."
Important to Be Truthful
Truth, Harpham says, is the most important thing parents with cancer can offer their children.
She says tell children to keep doing what children do -- going to school and playing with friends. And make sure your children don't feel guilty for worrying about themselves.
There are few children who haven't heard about the ravages of cancer, so experts say remind them not all cancers are the same.
"We have much more hope now than we've had in the past to think that we could either cure cancer or at least certainly treat it, so a person could live for a very, very long time," said Nancy Borstelmann, a social worker at the Dana Farber Cancer Institute in Boston.
The Dana Farber Cancer Institute brings together children whose parents have cancer, knowing the greatest hope comes when teens realize they are not alone.
It is why so many families and schools believe the DeWitt children are on to something with their documentary.
"There have been hundreds of requests for it," said Gabrielle.
"They've truly opened their hearts, their souls and lives to help others through their struggles," said DeWitt. "They did an amazing thing, and I'm very proud of them."
ABC News' David Muir filed this report for "World News Tonight."