Former Wales captain Matthew Rees is one of seven players who will leave Cardiff Blues at the end of the season.
The hooker, 34, joined from Scarlets in summer 2013 but was diagnosed with testicular cancer that October.
Rees underwent treatment and returned to playing, making Wales' squad to tour South Africa in June 2014.
Adam Jones, Filo Paulo, Simon Humberstone, Marc Breeze, Joaquin Tuculet and Lucas Amorosino are the other players leaving Blues.
Rees, who has won 60 Wales caps and three for the British and Irish Lions, is currently undergoing treatment on a shoulder injury.
There is no indication yet if Rees will join a new club or decide to call time on his career.
Billy Millard, Blues general manager, said: "We would like to thank all of the players for their commitment to Cardiff Blues during their time at the region and wish them well as they take up fresh challenges and the next stage of their careers.
"We will pay tribute to their contribution with presentations to them on the pitch following Saturday's home game with Zebre."
Fly-half Humberstone, 27, will join Doncaster Knights, having played in 14 games after making his debut against Worcester in 2013.
Basingstoke-born Humberstone has also played for Pontypridd.
"I'd like to say a massive thanks to everyone at Cardiff Blues for a fantastic spell and helping develop me as a player to this point in my career," he said.
"I am just looking forward to getting up to Doncaster now, training hard and hopefully contributing to helping them get back to where they want to be."