Jane Fonda has revealed she has been diagnosed with non-Hodgkin’s lymphoma, and the veteran American actor has started chemotherapy treatment.

Fonda, 84, revealed the news on Instagram, explaining it is a “very treatable cancer” and that she feels “very lucky” to have an illness many people survive.

The performer used the announcement to raise the issue of how many Americans “don’t have access to quality healthcare” due to insurance troubles and discussed the effects fossil fuels can have on people’s health.

In the post, she said: “So, my dear friends, I have something personal I want to share. I’ve been diagnosed with non-Hodgkin’s lymphoma and have started chemo treatments. This is a very treatable cancer. Eighty per cent of people survive, so I feel very lucky.

“I’m also lucky because I have health insurance and access to the best doctors and treatments. I realize, and it’s painful, that I am privileged in this. 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 healthcare I am receiving, and this is not right.

“We also need to be talking much more not just about cures but about causes so we can eliminate them. For example, people need to know that fossil fuels cause cancer. So do pesticides, many of which are fossil fuel-based.”

An outpouring of support and prayers for Fonda began within minutes of her announcement.

Famed comedian Chelsea Handler wrote via Instagram: “Love you, Jane. Thinking of you, always.”

The NBC anchor Andrea Mitchell said on Twitter: “She is such a leader and role model: wishing her the best as she deals with this.”

The Brazilian singer Luísa Sonza commented on Fonda’s Instagram post with “TE AMO”, Portuguese for “I love you.”

Other Twitter users echoes similar sentiments, with @lauraroslin writing: “Jane Fonda making her entire cancer announcement post about healthcare inequality, reducing environmental causes for cancer, and continuing her activism, I honestly don’t know a better person.”

Another user, @kenzvanunu, said: “Jane Fonda using her statement on her own diagnosis to point out how many families struggle with someone having cancer and not having health insurance or access to the same care she’s receiving is VERY JANE FONDA OF HER. sending her so much love.”

The Press Association contributed to this report