The problem:  If you’ve been diagnosed with prostate cancer, your doctor may suggest a CT or other scan to see whether the tumor has spread. But doctors can often tell how aggressive prostate cancer is by analyzing the biopsy results and looking at the prostate-specific antigen (PSA) levels in your blood.

When you might need a CT scan:  The test is necessary only if your biopsy score and PSA level suggest there’s a good chance that the cancer has spread.

Source: Consumer Reports on Health March 2015