Supreme Court Justice Ruth Bader Ginsburg said Saturday she’s “alive” and on her way to being “very well” following radiation treatment for cancer.

Ginsburg, 86, made the comments at the Library of Congress National Book Festival in Washington. The event came a little over a week after Ginsburg disclosed that she had completed three weeks of outpatient radiation therapy for a cancerous tumor on her pancreas and is now disease-free.

It is the fourth time over the past two decades that Ginsburg, the leader of the court’s liberal wing, has been treated for cancer. She had colorectal cancer in 1999, pancreatic cancer in 2009 and lung cancer surgery in December. Both liberals and conservatives watch the health of the court’s oldest justice closely because it’s understood the Supreme Court would shift right for decades if Republican President Donald Trump were to get the ability to nominate someone to replace her.

On Saturday, Ginsburg, who came out with the book “My Own Words” in 2016, spoke to an audience of more than 4,000 at Washington’s convention center. Near the beginning of an hour-long talk, her interviewer, NPR reporter Nina Totenberg, said: “Let me ask you a question that everyone here wants to ask, which is: How are you feeling? Why are you here instead of resting up for the term? And are you planning on staying in your current job?”

“How am I feeling? Well, first, this audience can see that I am alive,” Ginsburg said to applause and cheers. The comment was a seeming reference to the fact that when she was recuperating from lung cancer surgery earlier this year, some doubters demanded photographic proof that she was still living.

Ginsburg went on to say that she was “on my way” to being “very well.” As for her work on the Supreme Court, which is on its summer break and begins hearing arguments again Oct. 7, Ginsburg said she will “be prepared when the time comes.”

Ginsburg, who was appointed by Democratic President Bill Clinton in 1993, did not directly answer how long she plans to stay on the court. Earlier this summer, however, she reported a conversation she had with former Justice John Paul Stevens, who retired from the court in 2010.