The 84-year-old actor said Friday that Jane Fonda has non-Hodgkin lymphoma and has begun chemotherapy.
In an Instagram post, she broke the news and expressed her optimism in spite of the prognosis.
She claimed that so far, she has been handling chemotherapy well and that she still plans to fulfil her obligations.
The six-month course of chemotherapy is going well for Fonda, who said, "Believe me, I won't let any of this interfere with my climate work."
She also took advantage of the news to promote more equitable and open access to healthcare in the United States.
I am aware of my privilege in this, and it hurts," Fonda added. "Almost every family in America has dealt with cancer at some point,
it is wrong that too many people lack access to the kind of high-quality medical treatment I do."
Fonda has previously been diagnosed with breast cancer, though she revealed in 2010 that she was cancer-free.