By SABC Sport
27th July 2023
The Austria defender will now undergo several months of treatment for the cancer, which the Bundesliga club said was detected early and can be treated with medication.
They added there is an extremely high chance Lainer, 30, will make a full recovery and could return to professional football.
Sporting director Roland Virkus told the club's website: "We will do all we can to get Stevie the best possible treatment.
"We wish him and his family lots of strength and optimism in the fight against this disease."