Since Joan passed away at the age of 81, Rancic said she's just been trying to console and support Melissa Rivers, who serves as executive producer for Fashion Police.
"Melissa was Joan's world. I've been friends with Melissa a really long time and I'm just trying to help her out," Rancic told ABC News, adding that Joan's daughter is still grieving but will eventually play a pivotal role in deciding whether Fashion Police will continue on E!
"They are looking at different scenarios, whether it moves forward or it doesn't," Rancic said. "Melissa ... a lot of that will be up to her and how she's feeling and how she decides what she wants to do, along with the execs here at E! There is no word now... they are seeing what Fashion Police looks like without Joan."
Rancic apparently isn't sure whether the series can survive without the quick-witted and sharp Joan.
"A part of me is like Joan would want Melissa and us and the team to go on and I know she would, but it's just a matter of can there be a show without Joan?" Rancic told ABC News. "Do we want to do a Fashion Police without Joan? I don't know."
The Giuliana & Bill star also acknowledged how Joan's passing came as "the shock of a lifetime" for her.
"It really was," she said. "I had just seen Joan 48 hours before her procedure. We were taping the Emmy Fashion Police show and she was honestly better than ever and she even looked better than ever at 81."
Rancic had told Rivers how beautiful she looked at the time, a moment she can now look back on with happiness.
"She wasn't one to ever take a compliment, but she didn't say 'Stop it' that day. She just kind of smiled and said, 'Thank you,'" Rancic recalled.
"I'll never forget that, that moment. When this all happened, that was one of the first things I thought about... I just remember thinking, 'I'm just so happy we told her that day once again how much we love her and how beautiful she is, both inside and out.'"
She continued, "I still think she's going to walk through the door and yell, 'Giuliana, get back to work.' And it's hard to wrap my mind around never seeing her again. And I've experienced losing loved ones in my life and for some reason, this one is very different. You hear people say, 'He or she was larger than life.' Joan really was larger than life. I think that's a reason I can't imagine her gone."
Rancic also said she's thrilled to see the support flowing from all directions, showing how much Rivers will be missed both professionally and personally.
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"So many people care," Rancic noted. "It's amazing. I walk down the street and so many people will reach out for my hand and say, 'I'm so sorry about Joan...' She's gone, but she's not forgotten."