Ben Stiller revealed on SiriusXM's The Howard Stern Show Tuesday that he was diagnosed with "immediately aggressive" prostate cancer at the age of 48. 

The actor appeared on Howard Stern's program with his surgeon, Edward Schaeffer, and discussed his experience for the first time publicly. 
Ben said he had no family history of prostate cancer.
Even so, his doctor, Bernard Kruger, was able to detect the disease by conducting a Prostate-Specific Antigen (PSA) test during a yearly physical.
The blood test examines and measures the amount of PSA in a patient's blood, which is produced by cancerous and noncancerous tissue in the prostate.