Robin Quivers is opening up about a private battle.

In an exclusive interview with PEOPLE, the longtime co-host of "The Howard Stern Show" discussed her journey with endometrial cancer and how her community of support has encouraged her along the way.

In 2012, Quivers began experiencing trouble urinating, which led her to seek medical attention. During a visit to an emergency room, she learned that a mass the size of a grapefruit was on her pelvic area.

“It was painful, it was scary, it was bizarre,” Quivers told the publication.

After that, medical staff told her to see a doctor as soon as she returned home to New York City.

When Quivers arrived back in the Big Apple, she saw a gynecologist along with a gastroenterologist, but all tests came back inconclusive.

“Nobody was able to diagnose it,” she explained. “They told me, ‘We really don’t know what this is. We can’t identify it without going in and getting it.’”

During surgery, doctors discovered the mass had been resting on "every organ" in her pelvic region, which required a hysterectomy.

Quivers was diagnosed with a rare form of stage 3C endometrial cancer, which is estimated to affect 66,000 women in the United States this year, per the American Cancer Society. This cancer of the endometrium – the lining of the uterus – is the most common cancer of the female reproductive organs.

During her recovery, she endured 15-months of radiation and chemotherapy. Amid a difficult time, Quivers said that she found comfort from loved ones, including friend Howard Stern who “just surrounded me and made this network to take care of me. I never had to ask for anything. It was just overwhelming.”

After being in complete remission for over three years, the cancer returned Dec. 2016. Today, she receives immunotherapy infusions intermittently.

“When you’re in and out of treatment, you’re always recovering and trying to get back to where you were. I feel fine. It’s been 11 years of dealing with this — and I’m still here," she said.