Casillas: Buffon, Cech and I are the last rock stars in Europe
The former Spain captain, 37, has played in all four of his side's league matches this season, keeping clean sheets against Chaves and Moreirense.
Buffon, meanwhile, signed a contract with PSG in July that could see him play for the Ligue 1 champions until he is 42, while 36-year-old Cech is keeping new Arsenal signing Bernd Leno out of the team at Emirates Stadium.
Casillas thinks the hugely successful trio must continue to enjoy their remaining playing days as they draw closer towards retirement.
"We're the last rock stars, the oldest players who are still playing, at least on the European scene," he told Expresso.
"You have to enjoy the time that you still have left. At 37, though, you are nearer to retiring than continuing to play."
Casillas left Real Madrid in 2015 but had seen his status in the first team diminish in the 2012-13 season, when he clashed with then-head coach Jose Mourinho.
However, the five-time LaLiga winner has no interest in discussing his problems with the Manchester United boss now.
"After five or six years, you shouldn't talk about this," he said. "It's absurd now."
Preparados. #SomosPorto #UCLdraw pic.twitter.com/kag180IOgd
— Iker Casillas (@IkerCasillas) August 30, 2018