During her Oscar-winning career, documentary filmmaker Debra Chasnoff explored topics that were deeply personal to her.

In “Choosing Children” (1984), she profiled same-sex couples raising children together. With “It’s Elementary: Talking About Gay Issues in School” (1996), she promoted teaching young children about gay people. And through several more films over the last two decades, Chasnoff worked to raise the public’s awareness about the lives and struggles of LGBTQ Americans like her and many of her closest friends.

Her last film is by far her most personal. “Prognosis: Notes on Living,” follows Chasnoff, a longtime San Francisco resident, during the two years following her stage four metastatic breast cancer diagnosis. She died at age 60 in 2017.

The 82-minute film, which is this year’s local spotlight at the San Francisco Jewish Film Festival, will be screened in-person at the Castro Theatre on July 25 at 12 p.m., with a filmmakers Q&A to follow. The film also is available for online streaming during the festival from July 22 to Aug. 1.

“Documentary film has been a vehicle for me to be politically active … so this is very different for me to make a film where I’m the main character,” Chasnoff says early in “Prognosis.” She wonders: Is it fair to drag her family and friends into such an intimate and emotionally fraught project? “I do have something in my gut that says maybe this is worth it, not just for me but for many, many other people.”

Known to her friends as Chas, Chasnoff was “both integrally involved and letting go” of the film as it was being made, said producer and friend Joan Lefkowitz. “The collaboration was rich and full and difficult and loving,” she told J. “I wouldn’t trade it for anything, and I’m so glad it’s over.” (Lefkowitz edited Chasnoff’s short documentary “Deadly Deception,” about General Electric’s involvement in making nuclear weapons, which won an Academy Award in 1991.)

A small team of collaborators — including Lefkowitz and Nancy Otto, Chasnoff’s wife and partner for 17 years — filmed more than 200 hours of footage of Chasnoff, beginning shortly after she received her diagnosis. They captured her meeting with UCSF doctors and having procedures done (with permission from UCSF’s Carol Franc Buck Breast Care Center), getting her chemotherapy-thinned hair shaved by her son, Oscar (“You guys, it’s Uncle Fester,” she jokes of her new look), tending to her succulent garden at home and dancing at her 60th birthday party.

Kate Stilley Steiner, the film’s co-director and one of its cinematographers, said she felt tension between her dual roles of filmmaker and friend. “There were many moments when I would be filming something, and I would realize that what we were hearing was not good news,” she said. In those moments, she realized “that it was actually my job to keep the camera rolling and not have an emotional response to what was happening.”

Rabbi Stacy Friedman of Congregation Rodef Sholom in San Rafael appears in the documentary, singing and praying over Chasnoff as she slowly passes away. Friedman called Chasnoff, who was her cousin, “bravely honest” and “an instigator of change and progress.”

“Ultimately, the film that she, Nancy, and the extraordinary team created is a tremendous and unique gift to us all, one that will change the way we die, and influence how we live as well,” she wrote in an email to J. (Friedman revealed that she was diagnosed with breast cancer the same day Chasnoff died.)

Chasnoff was “very creative” in her practice of Judaism, which she mixed with elements of Buddhism, Lefkowitz said. Each year she would assemble her own Passover haggadah from various sources, and “it was something everyone looked forward to.” In a clip that didn’t make the final cut of the film, but that Stilley Steiner shared with J., Chasnoff is seen assembling a haggadah from pages scattered around the floor of her office. “I always feel the need to look for something better,” she explains to Otto, who is filming the scene.

Asked if the “Prognosis” team had any reservations about including scenes of Chasnoff struggling to breathe on her deathbed (and, in the end, of her lifeless body), Stilley Steiner replied, “From the very beginning, everyone was on board with it. I think that’s what makes it a really great film. If you aren’t willing to go the whole way, it negates the film itself.”

Otto, a nonprofit consultant and glass installation artist who now lives in Sonoma County, appears throughout “Prognosis.” She said she hopes the documentary helps viewers feel more comfortable having conversations with loved ones about mortality. The S.F.-based Koret Foundation is sponsoring the development of a discussion guide around the film in collaboration with the palliative care division of Jewish Family and Children’s Services.

“It’s an amazing feeling to feel like we finished Chas’ legacy,” she said. “This was a lasting thing that she wanted to give.”

“Prognosis: Notes on Living”

Streaming July 22 to Aug. 1, suggested viewing 12 p.m. July 31. In-person 12 p.m. July 25 at Castro Theatre. Not rated, 82 minutes. sfjff.org