The actress and businesswoman was best known for playing Chrissy Snow on the American sitcom as well as Carol Foster Lambert on Step By Step.

She died on Sunday, the day before her 77th birthday, at her home in California after living with breast cancer for more than 20 years.

"Suzanne Somers passed away peacefully at home in the early morning hours of 15 October," a statement from her publicist said.

"She survived an aggressive form of breast cancer for over 23 years. Suzanne was surrounded by her loving husband Alan, her son Bruce, and her immediate family.

"Her family was gathered to celebrate her 77th birthday on 16 October.

"Instead, they will celebrate her extraordinary life, and want to thank her millions of fans and followers who loved her dearly."

Somers revealed in an Instagram post in July that her breast cancer had returned.

"As you know, I had breast cancer two decades ago, and every now and then it pops up again, and I continue to bat it down," she wrote.

"I have used the best alternative and conventional treatments to combat it.

"This is not new territory for me. I know how to put on my battle gear and I'm a fighter."

She also praised her husband, Alan Hamel, who she said had been by her side "every step of the way".

"I can't even explain how much he has done for me. If it's even possible, we are even closer than ever," she added.

"My incredible family has been so supportive."

Somers was first diagnosed in 2000 and had previously battled skin cancer.

She faced backlash for relying on what she described as a chemical-free and organic lifestyle to treat her cancers.

She argued against the use of chemotherapy in books and on platforms like The Oprah Winfrey Show, which drew criticism from the American Cancer Society.

Somers starred in the first five series of Three's Company, starting in 1977, as the ditzy blonde friend alongside John Ritter and Joyce DeWitt.

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"Creating her was actually intellectual," she told CBS News in 2020. "How do I make her likeable and loveable... dumb blondes are annoying. I gave her a moral code. I imagined it was the childhood I would've liked to have had."

However, she was phased out of the show and fired when she asked for a raise from $30,000 an episode to $150,000.

"The show's response was, 'Who do you think you are?'" Somers told People in 2020. "They said, 'John Ritter is the star.'"

Her character was replaced by two different roommates for the remaining years the show aired.

Other television shows she appeared on in the 1970s included The Rockford Files, Magnum Force and The Six Million Dollar Man.

In the 1990s, she returned to the screen on the popular sitcom Step by Step.

She competed on Dancing with the Stars in the US in 2015 alongside partner Tony Dovolani.

Somers also wrote several self-help books and launched her own health and beauty product line.