Staging the Disease

Prostate cancer is a complex disease where patients may not need any treatment at all, or may require drastic intervention. Doctors use a staging system to determine where your cancer falls on the spectrum (the severity or extent) and to help you understand your treatment options and your prognosis. These stages include Localized, Locally Advanced, and Metastatic.

Localized prostate cancer means that the cancer is confined within the prostate. Locally advanced prostate cancer means that most of the cancer is confined within the prostate, but some has started to escape to the immediate surrounding tissues such as the capsule or seminal vesicles. In metastatic disease, the prostate cancer is growing outside the prostate and its immediate environs, often to lymph nodes but possibly to more distant organs. Lymph nodes are normal parts of the body that fight off infection. Lymphatic ducts connect organs like the prostate to lymph nodes, and prostate cancer can occasionally move along these ducts to spread into lymph nodes. There are hundreds of lymph nodes throughout the body, but prostate cancer tends to first spread to lymph nodes in the lower abdomen and pelvis. These can typically be seen using imaging studies. Also, during surgery, lymph nodes may be removed and examined for the presence of cancer cells. Cancers that spread to more distant organs tend to travel through the lymph system, a circulatory system similar to the blood stream that carries cells important in fighting infection and disease.

A number of tests can be used to help determine the stage of disease. For example, cancers growing outside of the prostate can often be detected through traditional imaging studies, such as CT scans, MRIs, or x-rays, or through more specialized imaging tests such as bone scans. Note that these imaging studies are not perfect – they are unable to detect very small groups of cancer cells. Results of these imaging tests alone cannot be used to determine the stage of the disease, to guide treatment options, or to predict outcomes. Knowing the stage of disease can help to determine how aggressively the disease needs to be treated, and how likely it is to be eradicated by the available treatment options.

In prostate cancer, we typically talk about localized disease (stage T1-T4) and metastatic disease (stages N1 and M1). The T score describes how much the prostate cancer has spread within the prostate and its surrounding structures. The N score describes if lymph nodes are involved with cancer, and the M score describes if cancer has spread to areas outside of the pelvis, like bone. We also refer to a clinical staging score which can be performed before surgery or radiation, and a surgical staging score, which can only be provided after surgery. Most men are currently diagnosed with clinical stage T1c, meaning that their cancers were diagnosed by PSA screening only, and are not detectable by imaging or by examination.

In general, we also talk about localized prostate cancer based on risk. Men with low risk prostate cancer will have a clinical T1c-T2a stage, a PSA under 10 ng/dl, and a Gleason sum of under 7. These men have a very low risk of dying from prostate cancer and generally do well with most forms of therapy, including active surveillance. Current clinical trials are attempting to show which of these men need definitive therapy and which men can be safely observed. This is the most common form of prostate cancer.

Men with high risk prostate cancer have clinical T2c and higher stage, Gleason 8 or higher grade, and PSA over 20 ng/dl. These men have a much higher risk of recurrence with surgery or radiation or surveillance, and often benefit from more aggressive combination approaches, which may include a clinical trial, in hopes of improving the outcomes for patients with high risk disease.

These men have a much higher risk of recurrence with surgery or radiation or surveillance, and often benefit from more aggressive combination approaches, and often clinical trials are attempting to improve upon these outcomes.

Men with intermediate risk prostate cancer fall in between, and have a PSA between 10 and 20 ng/dl, a clinical stage of T2b, and a Gleason 7 grade. Men with this kind of cancer are likely to benefit from treatment (surgery, radiation, seeds) and do well with this treatment.

See the figure to the right which describes the staging system.

❝ In prostate cancer, [genetic testing is] just not common because the common knowledge was that these mutations were very rare. But when we look in patients with advanced disease, they are actually very common ❞

- Dr. Joaquin Mateo

Terms to know from this article:

Prognosis

The likely outcome or course of a disease; the chance of recovery or recurrence.

Lymph nodes

A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph nodes filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called a lymph gland.

Screening

Checking for disease when there are no symptoms.

Gleason

Gleason Score (GS) - Gleason Grade: A system of grading prostate cancer cells based on how they look under a microscope. Gleason scores range from 2 to 10 and indicate how likely it is that a tumor will spread. A low Gleason score means the cancer cells are similar to normal prostate cells and are less likely to spread; a high Gleason score means the cancer cells are very different from normal and are more likely to spread.

Active Surveillance

Active surveillance is an option offered to patients with very low-risk prostate cancer (low grade, low stage, localized disease). Patients are monitored carefully over time for signs of disease progression. A PSA blood test and digital rectal exam (DRE) and prostate biopsy are performed at physician-specified intervals. Signs of disease progression will trigger immediate active treatment.

Grade

The grade of a tumor depends on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. Grading systems are different for each type of cancer.

Lymph

The clear fluid that travels through the lymphatic system and carries cells that help fight infections and other diseases. Also called lymphatic fluid.

PSA

prostate-specific antigen (PSA): A substance produced by the prostate that may be found in an increased amount in the blood of men who have prostate cancer, benign prostatic hyperplasia, or infection or inflammation of the prostate.

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