08/27/2008 AT 02:35 PM EDT
Losing her husband and sister to cancer "obliterated" Katie Couric's dream for a happy and intact family. Now she's doing everything she can to fight back and spare others the same pain.
In between raising her two daughters – Ellie, 17, and Carrie, 12 – and anchoring the CBS Evening News, she's teamed up with a group of powerhouse women to create Stand Up to Cancer
, a landmark, star-studded fund-raising special airing on Sept. 5 on NBC, CBS and ABC.
"[Cancer] completely destroyed my family twice. My husband, Jay, died when he was 42 and our daughters were 6 and 2," Couric tells PEOPLE exclusively in this week's issue. "Three years after that, my sister, Emily, who had ironically read the eulogy at my husband's funeral, was diagnosed with pancreatic cancer."
She adds, "My life has never been the same since. Both of their diagnoses were incredibly bleak and devastating."
And husband Jay is never far from their thoughts, Couric says.
"He comes up in conversation a lot. The girls may do something, and I'll say, 'Your dad did this too,' " she says. "My children have lived longer without their dad than they have with him. But that doesn't mean we don't miss him every day. I often think, 'He would be so proud of them.' "
After Jay and Emily's deaths, Couric cofounded the National Colorectal Cancer Research Alliance in 2001 to continue the fight. More recently, she learned how desperately funding is needed to make important advances in cancer research. And she has high hopes for the Stand Up to Cancer
"I hope enough money is raised so cancer researchers can come up with a cure," Couric says. "But realistically I hope that it will put cancer on the front burner and empower people to help move science along so that progress can be made."
For more on Katie Couric and her family's battle against cancer, pick up the latest issue of PEOPLE, on newsstands Friday. For more about Stand Up to Cancer, go to www.standup2cancer.orgRELATED GALLERIES:
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