British actor Andy Whitfield, who plays the title role in the Starz Original series Spartacus: Blood and Sand, was diagnosed with non-Hodgkin lymphoma.
He will begin treatment immediately.
The network said the cancer was discovered during a routine check-up as the 38-year-old Whitfield prepared to begin shooting the second season of the action-adventure series, which is filmed in New Zealand.
Starz said that production has been postponed while Mr Whitfield undergoes treatment.
According to the network, doctors say the cancer was detected in its early stages and is "very treatable".
Spartacus is based on the slave and folk hero from the 1st century BC. The show has been a breakout success for Starz since it premiered in January.
The first season concludes next month.