Cancer • The general term for a group of diseases in which body cells start to grow out of control.

Cancer grade • Best guess about how fast the cancer is probably growing (how aggressive it is). With prostate cancer, the grade is also called the Gleason Sum or Gleason Score.

Cancer stage • Tells about how big the cancer is and about how much it has probably spread.

Catheter • Tube used to drain the urine from the bladder. In men, the tube is put in through the penis.

Clinical trial • Research studies that test new drugs or procedures with less well-known or unknown effects or side effects.

Conformal radiation therapy • Conformal external beam radiation is a better way of directing the radiation to the prostate without spilling over to other tissues.

CT scan • An X-Ray procedure that uses a computer to look at many areas of the body. It can be used to tell if prostate cancer dhas spread.