Guests Ordered Not To Reveal Robin Quivers' Absence Amid Cancer Fears

The Howard Stern Show's SiriusXM studios have been emptier in recent weeks after Robin Quivers began working from home — sparking new fears over rumored health struggles.

Though the 63-year-old recently signed a new 5-year contract to stay on as Howard Stern’s sidekick, it’s become clear she doesn’t always feel up to making regular trips to the studio.

"Robin's not there. She speaks more slowly now, but she’s still funny as hell," a source told RadarOnline.com exclusively. "I know the executives want people to believe she’s there every day, but she’s not."

As recently as June 28, Stern Wack-Packer Fred the Elephant Boy made an in-studio appearance and was told by show staffers NOT to mention Quivers’ absence or that she was working from an ISDN line, the insider said.

Other sources say Quivers has been battling a secret condition.

"They all know, especially Howard, how much she means to the show and how it’s just not the same with her not being there. It might be better for everyone if they just told the truth," a source said of Quivers' possible health crisis.

Even Quivers’ close circle of friends were tight lipped when reached by RadarOnline.com.

"She’s doing okay," one former staffer said. "We text back and forth. She’s tired sometimes, but she says she’s doing okay."

Quivers, who has worked alongside the “King of All Media” for 30 years, announced in 2012 she needed surgery, radiation and chemotherapy to destroy tumors found in her bladder, pelvis and a grapefruit size mass in her uterus.