Zeta-Jones first revealed her diagnosis and decision to seek treatment in 2011, and returned to a healthcare facility at the end of April.
"Catherine has proactively checked into a healthcare facility," her representative, Cece Yorke, said. "Previously Catherine has said that she is committed to periodic care in order to manage her health in an optimum manner."
Douglas praised his wife's progress from Cannes, where he is in town to promote his HBO film "Behind the Candelabra."
"She's doing a really good job," he said. "I can't wait to see her. I'm proud of her."