When Jeopardy! host Alex Trebek was diagnosed with stage 4 pancreatic cancer three months ago, fans were shocked. But now the beloved Trebek has good news to share: He’s in “near remission,” according to doctors.

“It’s kind of mind-boggling,” the 78-year-old says, in PEOPLE’s new cover story. Although the cancer has a 9 percent survival rate, Trebek has been responding very well to chemotherapy. “The doctors said they hadn’t seen this kind of positive result in their memory…some of the tumors have already shrunk by more than 50 percent.”

RELATED: What to Know About Alex Trebek’s Stage 4 Pancreatic Cancer

Still, that doesn’t mean the longtime Jeopardy! host is totally out of the woods yet.

For more on Trebek’s treatment progress, pick up a copy of PEOPLE, on newsstands Friday

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Trebek says he’ll still have to go through several more rounds of chemotherapy to hopefully get into full remission, but he’s elated at how far he’s come.

He got emotional when he learned of the good news. “But they were tears of joy, not tears of depression,” he says. (Trebek has been honest about experiencing moments of deep sadness during the past three months.)

As for why he thinks he’s doing so well with the chemotherapy, which has left him weak and occasionally depressed, he mostly credits well wishes from fans and friends around the world.

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“I’ve got a couple million people out there who have expressed their good thoughts, their positive energy directed towards me and their prayers,” he says. “I told the doctors, this has to be more than just the chemo, and they agreed it could very well be an important part of this.”

He adds, “I’ve got a lot of love out there headed in my direction and a lot of prayer, and I will never ever minimize the value of that.”