Diagnosing and Staging Prostate Cancer

Patients with known or suspected prostate cancer will have several tests to confirm their diagnosis and assess the nature and extent of their disease. Prostate cancer diagnosis starts with:

• A blood test measuring the amount of prostate-specific antigen (also called PSA), in your blood
• A digital rectal exam (also called DRE) during which your doctor feels the prostate gland’s surface, searching for abnormalities like lumps or bumps
• Biopsy

Biopsy

Depending on the results of the first two steps, your doctor may recommend a tissue biopsy. This is typically an outpatient procedure. During a tissue biopsy procedure, several small tissue samples — usually 12 — are removed from the prostate gland. A pathologist will check the samples for abnormal cells.

The biopsy of prostate tissue is done with image guidance, which can be ultrasound, MRI or both. Your doctor will discuss pain control options with you depending on the type of biopsy you have.

There are several ways to perform a prostate biopsy.

• Transperineal biopsy: A needle is guided through the skin between the anus and the scrotum into the prostate gland to take tissue samples from different areas of the prostate.
• Transrectal biopsy: An ultrasound probe is inserted into the rectum to guide the needle and take biopsies.
• Targeted biopsy: MR fusion is another way to take tissue biopsies from the prostate gland. It is called a targeted biopsy because, using MR imaging, the doctor can locate the area of the prostate where cancer is believed to be located and biopsy just that area.

Prostate Cancer Grading and Staging

Our pathologists are important members of the prostate cancer care team and specialize in specific areas of the anatomy — in this case, cancers of the genitourinary system. The information they provide helps guide personalized treatment decisions with the goal of giving you the best possible outcome.

Grading

Pathologists look at biopsied prostate tissue under the microscope to determine if prostate cancer is present. If cancer is found, the pathologist further evaluates how abnormal the cells look under the microscope compared to normal prostate tissue. This process is the Gleason Grading System and can help predict how aggressively the tumor will behave.

• Grades 1 and 2: Closely resembles normal prostate gland tissue; no longer considered to represent cancer
• Grade 3: Cancer forms glands with some features that are not normal
• Grade 4: Cancer glands are more abnormal including joining together or breaking apart
• Grade 5: Cancer glands are very abnormal including forming solid sheets or breaking into single cells

Each biopsy receives two Gleason grades representing the most common grade and the highest grade found in the tissue. These grades are added together to form the Gleason score. For example, if most of the tumor is grade 3 and a smaller portion is grade 4, the grades are added together, forming a Gleason score of 7.

These findings may also be written out as grade groups instead of Gleason scores. Prostate cancer Gleason scores in grade group 1 tend to grow and spread slowly (if at all), while scores for prostate cancers falling into grade group 5 have the greatest potential to grow and spread quickly.

• Grade group 1: Gleason score of 6
• Grade group 2: Gleason score of 7; most of the tissue is scored as 3, with the lesser amount being 4
• Grade group 3: Gleason score of 7; most of the tissue is scored as 4, with the lesser amount being 3
• Grade group 4: Gleason score of 8
• Grade group 5: Gleason scores of 9 and 10

Staging

If a you have surgery to remove the prostate gland, the pathologist evaluates the prostate tissue under a microscope to determine the prostate cancer stage. There are four stages of prostate cancer (I-IV), which are further categorized with letters depending on the seriousness of the disease: IIIA, IIB, IIC, IIIA, IIIB, IIIC, IVA, IVB.

The stage of your prostate cancer describes the extent of the cancer and if it has spread or metastasized. If the cancer has spread, staging also provides your care team with information about the parts of the body to which the cancer has spread. Staging helps your doctor understand how to treat your cancer and your prognosis. Like other types of cancer, prostate cancer is staged according to the American Joint Committee on Cancer and its TNM system. TNM stands for:

• T = The extent of the primary tumor (primary means where the cancer originated)
• N = If the cancer has spread to nearby lymph nodes
• M = If the cancer has spread or metastasized to other parts of the body

After a pathologist confirms the prostate cancer diagnosis, physicians take extra steps to determine if the cancer has spread outside the prostate.

Imaging

• Magnetic resonance imaging (MRI) scans evaluate the area around the prostate gland.
• Computerized tomography (CT) scan helps detect cancer in lymph nodes.
• Bone scan checks if prostate cancer has spread to the bones.
• Positron emission tomography computerized tomography (PET/CT) scan detects prostate-specific membrane antigen (PSMA), a protein found on prostate cancer cells. This type of scan can find cancer with low prostate-specific antigen (PSA) levels or small tumors. It may be used if your doctor suspects prostate cancer has spread or returned after treatment or if results from other types of imaging are inconclusive.

Molecular Testing

Most prostate gland tissue samples, around 75%, will test negative for cancer, meaning there was no evidence of cancer in the tissue when it was evaluated by a pathologist. However, it is possible to get a false negative. Your doctor may consider other factors in your case and recommend molecular testing. A molecular test looks at changes in your genes (mutations) or specific changes in proteins in cells. If cancer is confirmed, these tests help predict drugs that will be most effective in treating the cancer. The drugs are called targeted therapies.