Award-winning US actress and activist Jane Fonda said she has begun treatment and vowed to fight the "very treatable" illness. The 84-year-old shared the news of her condition in a post on social media.

US actress Jane Fonda announced on Friday that she had been diagnosed with non-Hodgkin's Lymphoma and had begun a 6-month course of chemotherapy treatment.

Non-Hodgkin lymphoma is a form of cancer that begins in the white blood cells and affects parts of the body's immune system.

The 84-year-old Oscar winner said, "This is a very treatable cancer. 80% of people survive, so I feel very lucky."

Fonda shared the news of her illness in an Instagram post in which she spoke of her access to health insurance along with the best doctors and treatments, and added, "I realize, and it's painful, that I am privileged in this."

Fonda uses illness to highlight issues in health care

Well known for her activism, Fonda also pointed out that while she was fortunate to be receiving such treatment, the same could not be said for others who found themselves in a similar situation.

"Almost every family in America has had to deal with cancer at one time or another and far too many don't have access to the quality health care I am receiving and this is not right," Fonda said.

The environmentalist and social campaigner said that she would not let her treatment interfere with her climate activism, and even pointed to the upcoming midterm elections, saying that she would be there.

"The midterms are looming, and they are beyond consequential so you can count on me to be right there together with you as we grow our army of climate champions," Fonda said.

Fonda has been in film and television for more than six decades and won the Oscars for roles in the 1971 movie Klute and 1978's Coming Home. Her latest film, Moving On, will premiere at the Toronto Film Festival this month.

She also starred in the final season of Netflix comedy Grace and Frankie.