|Dmitri Hvorostovsky (Photo: Pavel Antonov)|
Hvorostovsky was diagnosed with a brain tumor in 2015. He has continued performing since them but has occasionally been forced to pull out of scheduled roles. His website currently lists no upcoming performances.
He was due to play leading roles in Verdi's Un ballo in maschera, Otello and Rigoletto in Vienna this year and next. A statement yesterday says replacements will be announced later.