The last time Melissa Gilbert spent time with her TV dad was just a week before his death.

Michael Landon, the "Bonanza" actor who starred as beloved patriarch Charles Ingalls on "Little House on the Prairie," died three months after publicly announcing his pancreatic cancer diagnosis in 1991. He was 54.

Gilbert, who played "Half Pint" Laura Ingalls in the series, is teaming up with the Pancreatic Cancer Action Network (PanCAN). The nonprofit aims to fund research, provide patient/caregiver support, and advocate for increased federal research funding for those affected by the disease.

‘LITTLE HOUSE’ STAR MICHAEL LANDON WAS STUBBORN, AVOIDED DOCTORS AHEAD OF FATAL CANCER DIAGNOSIS: DAUGHTER

Melissa Gilbert wearing a white dress smiling at her TV dad Michael Landon also wearing white

Melissa Gilbert is seen here with her TV dad Michael Landon on the set of "Little House on the Prairie." (ALAMY)

"I had been running from the grieving process my whole life and trying to avoid it. But it was really important for me to go and have that goodbye time, which I didn’t have with my father. . . . This was a chance to gift myself with that goodbye and say to him all the things I needed to say."

— Melissa Gilbert

"His daughter Leslie Landon Matthews, someone who has been a very dear friend of mine for 50 years, called me because she wanted me to know [his diagnosis] before it hit the press," Gilbert told Fox News Digital. "Her dad was going to do a press conference, and she didn’t want me to just hear about it. So she called and told me . . . I was gutted."

"My first thought was, ‘This is horrible – I’m going to lose a mentor and father figure,’" the 60-year-old recalled. "I’d already lost my own father to suicide when I was 11. I was staring down the barrel of losing another important male influence in my life. It really shook me."

The cast of Little House on the Prairie posing together.

The cast of "Little House on the Prairie." From left: Melissa Gilbert as Laura Elizabeth Ingall, Michael Landon as Charles Philip Ingalls, Karen Grassle as Caroline Quiner Holbrook Ingalls, Melissa Sue Anderson as Mary Ingalls Kendall, Lindsay/Sydney Greenbush as Carrie Ingalls. (NBCU Photo Bank/NBCUniversal via Getty Images via Getty Images)

"Like everyone else, I sort of watched from a distance because I didn’t want to intrude," said Gilbert. "But then a while later, I made the decision that I really had to go see him. And this was much later on in his pancreatic cancer journey. I ended up going and spending time with him. And it turned out to be just a week before he died."

Melissa Gilbert holding her purple lifestyle collection

Modern Prairie co-founder Melissa Gilbert (pictured here) and her business partner Nicole Haase, are teaming up with the Pancreatic Cancer Action Network (PanCAN) to launch a special capsule collection from their lifestyle brand. Purchases from the Modern Prairie x PanCAN collection will fund PanCAN’s resources, services and research that drive progress toward the disease. (Modern Prairie)

In November – Pancreatic Cancer Awareness Month – Gilbert’s lifestyle brand, Modern Prairie, is launching a special collection featuring purple, the official color of pancreatic cancer awareness. All proceeds from the collection will support PanCAN.

Memories of Gilbert's last meeting with Landon have been vivid in her mind.

Michael Landon looking up at the sky wearing a white shirt.

Michael Landon announced his pancreatic cancer diagnosis three months before his death. (Frank Carroll/NBCU Photo Bank/NBCUniversal via Getty Images via Getty Images)

"It was very hard," she admitted. "I had been running from the grieving process my whole life and trying to avoid it. But it was really important for me to go and have that goodbye time, which I didn’t have with my father. . . . This was a chance to gift myself with that goodbye and say to him all the things I needed to say."

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Melissa Gilbert embracing her TV dad Michael Landon in costume.

Melissa Gilbert lost her mentor, acting partner, favorite director, father figure, friend and boss, Michael Landon, in 1991 to pancreatic cancer.  (Frank Carroll/NBCU/Getty Images)

Gilbert described the meeting as "really hard and painful," but one that she said was blessed "with a lot of humor."

"There were always funny moments with Michael," she said. "Even as sick as he was, he still maintained his incredible sense of humor. I remember my son Dakota was about two at the time, and one of Michael’s horses bit him on the finger. I didn’t want Mike to know until we knew how bad it was. It turned out it was nothing."

A close-up of Michael Landon sick with pancreatic cancer.

Michael Landon in May 1991. He passed away in July of that year. (Kypros/Getty Images)

"I went in the room to sit with Mike, and he said, ‘Did one of the horses bite the kid?’" Gilbert continued. "I said, ‘Oh my gosh, I’m so sorry. I didn’t want you to know that. He said, ‘Well, is he OK?’ I said, ‘Yeah, he’s fine.’ He said, ‘Thank God it wasn’t worse. I would feel awful.’ And then he said, ‘Wait a minute, I’m dying from pancreatic cancer. How could I feel any worse?’"

Michael Landon playing with Melissa Gilberts pigtails.

Melissa Gilbert's last meeting with Michael Landon was heartbreaking, but there were also moments of humor. (ALAMY)

"It made me laugh," said Gilbert. "But it also broke my heart a little bit, knowing that this incredible person, who was able to find humor . . . was no longer going to be around to help me do that."

The actress described Landon as a fighter, someone who was "trying everything" to combat the disease.

A close-up of Michael Landon smiling with grey hair

Michael Landon was determined to fight the disease. (Art Zelin/Getty Images)

"He was trying conventional treatments, he was trying holistic and Eastern treatments, he was doing everything he possibly could to fight it," Gilbert explained. "It was one of the reasons why I wasn’t able to see him sooner. He was always in a hospital, a treatment center, or a holistic medicine center. He even talked about doing coffee enemas. He was constantly searching, trying and fighting. It wasn’t until very close to the end that everybody realized that it was the end . . . nothing worked."

WATCH: ‘LITTLE HOUSE’ STAR MICHAEL LANDON WAS STUBBORN ABOUT HIS HEALTH: DAUGHTER

According to PanCAN, pancreatic cancer is the third leading cause of cancer-related death in the United States. It has a five-year survival rate of 13%. It noted that there is no standard early-detection test, and there are few effective treatment options.

The actress said she was "non-functional for quite a while" after Landon died.

Melissa Gilbert at the "Nymphes DOr - Golden Nymphs" Nominees Party.

Melissa Gilbert told Fox News Digital she was "non-functional for quite a while" after Michael Landon died. (Pascal Le Segretain/Getty Images)

"I remember drinking a lot of vanilla malts for some reason," said Gilbert. "I don’t know why that sticks in my brain. My family surrounded me and kept me going. I had a small child at home to take care of. Seeing this gorgeous boy, my son Dakota . . . was my light at the end of the tunnel. There was sorrow, grief and depression taking care of him, but he brought a lot of sunshine into my life."

Melissa Gilbert smiling and standing next to Michael Landon as they both wear white.

"Michael Landon was one of the greatest influences on my life," said Melissa Gilbert. "His death left an enormous hole in the lives of those of us who knew him personally as well as those who simply admired his work." (Frank Carroll/NBCU Photo Bank/Getty Images)

"I remember my sister coming over every day just to hang out," said Gilbert. "My friends were really helpful – it helped a lot to talk about Michael, to talk about who he was and how he impacted my life. It was a very difficult and sad time. . . . [But] I promised I would allow myself to grieve and not deny my feelings this time around. And I did, but it was hard."

Michael Landon surrounded by his children.

Michael Landon is seen here surrounded by his family. (Ron Galella, Ltd./Ron Galella Collection via Getty Images)

"It also helped me a lot to dedicate myself towards helping Michael Landon’s family get through this too, to support them in their grief," she pointed out. "It got me out of my head . . . the pain softened and eventually became easier to deal with."

It wouldn’t be the last time Gilbert would lose a loved one to the disease.

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Melissa Gilbert embracing a smiling Patrick Swayze

Melissa Gilbert with her pal Patrick "Buddy" Swayze. (Bruce Glikas/FilmMagic/Getty Images)

Her friend, Patrick Swayze, was diagnosed with pancreatic cancer in 2008. He died a year later at age 57.

"I remember hearing about his diagnosis and thinking, ‘Oh my God, he’s going to die,’" Gilbert admitted. "I know Buddy said, ‘I’m going to beat it. I’m going to get through this.’ I watched him battle and battle . . . the time he was able to squeeze out of that diagnosis was nothing short of miraculous. I think so much of that was because treatments had changed a bit. . . . It may not have spread as far as Michael’s did at that point. But I do think the journey is different for everyone."

Patrick Swayze and his wife Lisa Niemi Swayze hugging and smiling

Patrick Swayze is seen here with his wife Lisa Niemi Swayze. (Vinnie Zuffante/Getty Images)

"I’m so grateful that he had his family and his extraordinary wife, Lisa, there to support him through all of this," said Gilbert. "I tried to keep my distance because I didn’t want to be intrusive.

Patrick Swayze at a press event before passing away from pancreatic cancer

Patrick Swayze in 2008. In 2009, Melissa Gilbert lost her dear friend, whom she had known since the early '80s.  (Barry Brecheisen/WireImage for Rockit Ranch Productions/Getty Images)

"At one point, I was the president of the Screen Actors Guild. There was a glitch with his insurance, and he was being denied coverage for a treatment. He called me, and I was able to make a phone call and clear the log jam so that he could get the treatment that he needed. For me, that was an incredible sense of accomplishment of being able to do something for Buddy."

A close-up of Patrick Swayze wearing a black shirt

"Years later, when I learned that Patrick [Swayze] was diagnosed, I was terrified for him," said Melissa Gilbert. "Obviously, this is not a fight I can take on myself and that is why I am so grateful for PanCAN. PanCAN is truly a one-of-a-kind resource for people whose lives are impacted by pancreatic cancer." (Kevin Winter/Getty Images)

"It was the thing that I couldn’t do for Michael Landon," she said quietly. "I felt like I was able to pick up my sword and go to battle for Buddy Swayze. . . . When he did pass, there was incredible sorrow . . . it was a feeling of, ‘There goes another good one. Damn it, this horrible disease.’ I had this feeling of, ‘I have to do something. I’m going to fight.’"

Gilbert said she’s grateful to create a special collection that would not only honor "two powerful physical specimens of men," but all the many others across the country who are fighting the illness.

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Jonathan Frakes embracing Lisa Niemi Swayze

Jonathan Frakes and Lisa Niemi Swayze, Patrick Swayze's widow, attend the PanCAN PurpleStride: The Ultimate Event To End Pancreatic Cancer event at Santa Monica Pier on April 27, 2024, in Santa Monica, California.  (David Livingston/Getty Images)

"They both said, ‘I’m going to beat it,’" said Gilbert. "And it’s really important for people to understand that supporting one cancer research benefits all the others. As research develops, as treatments and cures are developed, it can eventually be applied to other cancers. . . . Pancreatic cancer is a horrible thing to experience, but we can detect things earlier as research grows."

"Make no mistake, all cancers are cruel," she said. "But the survival rate for pancreatic cancer is abysmal. And the reason for that is that it’s so hard to detect, and it goes fast. This cancer is particularly bad because it is so sneaky. . . . But I’m still going to fight."