Robin Quivers -- RETURNS TO HOWARD STERN STUDIO ... After Cancer Battle

For the first time in 17 months, Robin Quivers returned to her spot in the studio on the Howard Stern show ... with Howard telling his BFF, "Never get sick again."

As we previously reported, Quivers had been participating on the show from her home ... while she was being treated for cancer.

But Quivers says she's cured -- and today, she returned to her famous glass box in Howard's studio to participate on the SiriusXM radio show.

"Seriously, I've been praying for this day ... and I'm really happy that you are here," Howard said.

He continued, "Honestly, I did not think this day would come."

"I was very very depressed over your illness. I wasn't sure what the outcome was going to be. There was a time I really did think I was going to lose you permanently. And I'll tell you what, this is a pretty remarkable day that you are here triumphant and cured. I never would have predicted this. Honestly."

Welcome back.

7:55 AM PT -- We got Robin on her way out of the studio this morning ... and she told us how special it is to have a friend like Howard Stern, who cares so deeply about her.

"We know we love each other," Robin told us ... adding, "[the cancer scare] gave us an opportunity to express what's always been there."