A diagnosis of prostate cancer generally takes place in three steps.
A digital rectal exam (DRE) or a prostate-specific antigen (PSA) blood test can indicate problems with the prostate but cannot confirm prostate cancer for certain. These tests are commonly performed on all men above a certain age. Depending on other risk factors, this age may range from 40 to 60.
If initial screening tests indicate a need, a doctor will take a small sample of tissue—biopsy—from the prostate. The sample is then examined under a microscope for signs of cancerous cells. Biopsy is the only way to confirm prostate cancer. The biopsy is obtained via needle into the prostate which is accessed through the rectum.
Once a prostate-cancer diagnosis is confirmed, doctors must determine how extensive the cancer is before deciding how to treat it. Several postdiagnostic tests—including blood tests, computed tomography (CT or CAT) scans, magnetic resonance imaging (MRI) scans, and bone scans—are used to establish the cancer's stage using the following scale:
Stage I Prostate Cancer
Cancerous tumors affect only a small area of the prostate and generally cannot be felt during a DRE or detected via ultrasound; the cancer has not spread outside the prostate.
Stage II Prostate Cancer
The cancer affects more of the prostate and may be seen on ultrasound or felt during a DRE; the cancer has not spread outside the prostate.
Stage III Prostate Cancer
Cancer cells have spread to other tissues near the prostate, such as the seminal vesicles, but are not present in lymph nodes or other parts of the body.
Stage IV Prostate Cancer
Cancer cells have metastasized to the lymph nodes or other parts of the body or have spread to a large amount of the surrounding tissue, such as the bladder or rectum.