David Prowse , who played Darth Vader in `` Star Wars , '' has prostate cancer . Score: 7 Actor said every man over 50 should have a blood test for prostate cancer .
David Prowse , who played Darth Vader in `` Star Wars , '' has prostate cancer . Prowse says he is undergoing radiotherapy at hospital in south London . Actor said every man over 50 should have a blood test for prostate cancer .