Joosten, who was also known for playing the president's secretary in the TV series "The West Wing," died Saturday at her Westlake Village home, said her daughter-in-law, Jeremy Joosten.
lung-cancer awareness and research, she agreed to the plot turn on "Housewives" that mirrored her off-screen life.
PHOTOS: Notable deaths of 2012
"This will allow the public to much more comfortably talk about lung cancer," Joosten told the New York Post in February.
The most challenging aspect of the lung-cancer story arc, she said in another interview, was "working with the producers to make sure the material was true and accurate. They have been wonderful about that.
"Secondly, I joke about this being a practice session, but there is a cathartic aspect to it," Joosten said in February on MetroSeeker.com.
Last fall, she called herself a "two-time lung cancer survivor" in a first-person account of the disease that she wrote for The Times.
"My first was in 2001 and my second was in 2009, two completely different lung cancers, one on each side. I am the only 'celebrity' to be public about my lung cancer.
"So far, I am a cancer survivor, but cancer will be with me for the rest of my life, be it as a nodule, tumor or cell someplace, or in my fears and anxieties," she wrote. "Therefore I've decided that I am 'living with cancer.'"
The actress started smoking when she was 16 but quit after her first lung cancer diagnosis, her publicist told The Times in 2009.
On "Housewives" and "The West Wing," Joosten was known for making the most of her sometimes limited scenes, "delivering withering one-liners in her crazy/wise style," The Times said last year.
She had played Karen McCluskey on the hit ABC show since 2005.
Felicity Huffman, one of her "Housewives" costars, wrote Saturday on her Twitter account: "She was an amazing woman and a wonderful actress."
Born Dec. 20, 1939, in Chicago, Joosten did not begin to pursue her "childhood dream" of acting until she was 42.
Previously, she had worked as a psychiatric nurse in a Chicago hospital, where she met and married a psychiatrist. They had two sons, and she embraced life as a suburban housewife in upscale Lake Forest near Chicago.
In 1980 her husband's alcoholism led to a divorce, according to her website, which also says she often supported her family by hanging wallpaper and painting her neighbors' mansions. She would then book many of these same homes for location filming and print ads.
Joosten's mother died in her 40s, and Joosten vowed that she wouldn't have similar regrets at the end of her life.
"She was very angry when she died, because she had literally put off so many things she wanted to do" because of time or money, Joosten said in 2009 in the Oklahoman. "That was a huge lesson for me. I didn't want to get to the end of my life thinking, 'Gosh, if I had only tried…."