Prostate Cancer

Staging

How Is Prostate Cancer Staged?

If the prostate biopsy finds a cancer, more tests are done to find out how far the cancer has spread within the prostate, or nearby tissues or other parts of the body. Staging is the process of gathering information about a cancer from certain examinations and diagnostic tests to determine how widespread it is. The stage of a cancer is the most important factor in choosing treatment options and predicting a patient's outlook for survival. The tests that are done for staging prostate cancer are often based on the man's DRE results, PSA blood test results, and the Gleason score of his cancer.

Physical Examination

The physical exam, especially the digital rectal examination, is an important part of prostate cancer staging. The doctor doing the DRE can tell whether it is likely that the cancer is limited to one side of the prostate, whether it has spread to the other side as well, and if it has probably spread beyond the prostate gland. The DRE is also used together with the PSA blood test for early detection of prostate cancer, and is discussed in the Detection Section.

Imaging Tests Used for Prostate Cancer Staging

Computed tomography: Commonly known as a CT or CAT scan, this test uses a rotating x-ray beam to create a series of pictures of your body from many angles. A computer combines the information from all these pictures to produce a detailed cross-sectional image. To highlight details on the CT scan, you may be asked for permission to have a harmless dye injected.

The CT scan may reveal abnormally enlarged lymph nodes. Lymph nodes are a network of bean-sized collections of white blood cells that fight infection. Some prostate cancers spread to nearby lymph nodes, called pelvic lymph nodes. Enlarged pelvic lymph nodes could be a sign of a spreading cancer, or could mean that your body is fighting an infection.

Magnetic resonance imaging (MRI): MRI is like a CT scan except that magnetic fields are used instead of x-rays to create detailed cross-sectional pictures of selected areas of your body. These pictures can show abnormal areas of bones or lymph nodes that suggest cancer may have spread from the prostate.

Radionuclide bone scan: This procedure helps show whether the cancer has spread from the prostate gland to bones. The patient receives an injection of radioactive material. The injection itself is the only uncomfortable part of the entire scanning procedure. The amount of radioactivity involved is low in comparison to the much higher doses used in radiation therapy, and this low level of radiation does not cause any side effects. The radioactive substance is attracted to diseased bone cells throughout the entire skeleton. Areas of diseased bone will be seen on the bone scan image as dense, gray areas, called "hot spots." These areas may suggest metastatic cancer is present, but arthritis or other bone diseases could also cause the same pattern. To distinguish among these conditions, the cancer care team may use other imaging tests or take bone biopsies.

Prostascint scan: Like the bone scan, the prostascint scan uses low level radioactive material to find cancer that has spread beyond the prostate. Both tests look for areas of the body where the radioactive material collects. But there are several important differences between the two tests.

The radioactive material used for the bone scan collects in areas of damaged bone that may be caused by prostate cancer, other cancers, or benign conditions. The radioactive material for the prostascint scan is attached to a monoclonal antibody, a type of antibody manufactured in the laboratory to recognize and stick to a particular substance. In this case, the antibody specifically recognizes prostate-specific membrane antigen (PSMA), a substance found only in normal and cancerous prostate cells.

The advantage of this test is that it detects spread of prostate cancer to bone as well as lymph nodes and other organs, and that it can clearly distinguish prostate cancer from other cancers and benign disorders. Some doctors believe this test is useful in finding metastatic prostate cancer in newly diagnosed patients whose cancer at first appears to be localized to the prostate. The test may also be used when a patient's blood PSA level begins to rise after a period of remission following definitive therapy, but when other tests are not able to find the exact location of the recurrent cancer.

Lymph Node Biopsy

This procedure may be done to find out if cancer has spread from the prostate to nearby lymph nodes. If cancer cells are found in the lymph node biopsy specimen, curative surgery is usually not attempted and other treatment options are considered. There are several options for doing lymph node biopsies.

The surgeon may remove lymph nodes through an incision in the lower part of the abdomen. This is done in the same operation as the planned radical prostatectomy. The nodes are tested in the lab while you are under anesthesia to decide whether the surgeon should continue the radical prostatectomy.

A specially trained radiologist may take a sample of cells from a lymph node by using a technique called fine needle aspiration (FNA). In this procedure, the doctor uses the CT scan image to guide a long, thin needle into the lymph nodes. The syringe attached to the needle takes a small tissue sample from one of the lymph nodes. There is no incision, no scar, and the patient can return home a few hours after the procedure.

A surgeon may use a laparoscope, which is a long, slender tube inserted into the abdomen through a very small incision. The laparoscope allows the surgeon to view lymph nodes near the prostate and remove these pelvic lymph nodes using special surgical instruments operated through the laparoscope. Because no large incisions are involved, most people recover fully in only one or two days, and there is virtually no scar left after the operation.

The TNM Staging System

A staging system is a standardized way in which the cancer care team describes the extent to which a cancer has spread. While there are several different staging systems for prostate cancer, the most widely used system in the United States is called the TNM System (also known as the Staging System of the American Joint Committee on Cancer). The TNM System describes the extent of the primary tumor (T stage), the absence or presence of spread to nearby lymph nodes (N stage), and the absence or presence of distant metastasis (M stage).

T stages: There are actually two types of T classifications for prostate cancer. The clinical stage is based on digital rectal exam, needle biopsy, and transrectal ultrasound findings. The pathologic stage is based on surgical removal and examination of the entire prostate gland, both seminal vesicles (two small sacs next to the prostate that store semen) and, in some cases, nearby lymph nodes.

Knowing the clinical stage is important because this information is used in making treatment decisions, such as whether a patient might benefit from surgical removal of the prostate. However, the clinical stage may underestimate the extent of cancer spread, and the pathologic stage determined after surgery is more accurate in predicting the patient's outlook for survival. Men who do not have a radical prostatectomy as their main treatment do not have a pathologic T stage determined.

There are four categories for describing the prostate tumor's (T) stage, ranging from T1 to T4.

• • T1 refers to a tumor that can't be felt during a digital rectal exam, but cancer cells are found in a biopsy specimen. T1 prostate cancers can be further subclassified as T1a, T1b, and T1c. T1a and T1b describe prostate cancers found incidentally (by "accident") during TURP (transurethral resection of the prostate), a kind of prostate surgery done to relieve symptoms of benign (noncancerous) prostate enlargement. This operation is usually done because the enlarged prostate gland presses on the urethra (the tube connecting the bladder and penis). This makes it difficult for a man to urinate.
  When prostate tissue is removed and checked under the microscope, cancer may be found, even though the doctor who removed the tissue did not expect cancer to be present. T1a indicates that less than 5% of the tissue removed is cancer and more than 95% is benign. If more than 5% is cancer, it is classified as T1b. T1c cancers are also found only by biopsy, but in these cases a core needle biopsy is done because the PSA blood test result suggested that a cancer might be present.
• • T2 means that a doctor can feel the prostate cancer by digital rectal exam (DRE) and that the cancer remains within the prostate gland. This category is also subclassified into T2a or T2b. T2a means that the tumor involves only the right or left side of the prostate, but not both sides. If both the left and right sides are involved, it is a T2b cancer.
• • T3 cancers have spread to the connective tissue next to the prostate and/or to the seminal vesicles, but do not involve any other organs. This group is divided into T3a and T3b. In T3a, the cancer extends outside one or both sides of the prostate, but has not spread to the seminal vesicles (two small sacs next to the prostate that store semen). With T3b, the cancer has spread to the seminal vesicles.
• • T4 means that the cancer has spread to tissues next to the prostate (other than the seminal vesicles), such as the bladder's external sphincter (muscles that help control urination), the rectum, and/or the wall of the pelvis.

N stages: N0 means that the cancer has not spread to any lymph nodes. N1 indicates spread to one or more regional (nearby) lymph nodes in the pelvis.

M stages: M0 means that the cancer has not metastasized beyond the regional nodes. M1 means metastases are present in distant (outside of the pelvis) lymph nodes, in bones, or other distant organs such as lungs, liver, or brain.

Stage Grouping

Once a patient's T, N, and M categories have been determined, this information is combined in a process called stage grouping to determine the stage, expressed in Roman numerals from I (the least advanced) to IV (the most advanced stage). The TNM procedures for stage grouping are usually outlined as a table. Some patients find this information useful in understanding their stage and in discussing treatment options with their doctors. Other patients may find this a little overwhelming. The important point is that if you have any questions about your prostate cancer and your treatment options, ask your cancer care team.

AJCC (TNM) Stage Groupings
Stage I	T1a, N0, M0, low grade or score
Stage II	T1a, N0, M0, intermediate or high grade or score
	T1b, N0, M0, any grade or score
	T1c, N0, M0, any grade or score
	T1, N0, M0, any grade or score
	T2, N0, M0, any grade or score
Stage III	T3, N0, M0, any grade or score
Stage IV	T4, N0, M0, any grade or score
	Any T, N1, M0, any grade or score
	Any T, any N, M1, any grade or score

In addition to the TNM system, other systems may be used to stage prostate cancer. The Whitmore-Jewett system classifies prostate cancer as A, B, C, or D. If your doctors use this system, they can translate it into the TNM system or can explain how their staging will determine your treatment options.

Source: AMERICAN CANCER SOCIETY