Risk Assessment for Prostate Cancer

With the widespread use of prostate-specific antigen (PSA) testing to identify men at increased risk of prostate cancer, more individuals have been diagnosed with prostate cancer than in the period before PSA testing was widely available (pre-1992). Cancers diagnosed through PSA testing are often early stage or less advanced cancers. According to data from the National Cancer Institute, more than 90 percent of all prostate cancers are now diagnosed at a less advanced stage and men are surviving longer after diagnosis and treatment.

Once prostate cancer is diagnosed, you and your doctor must go through a process of risk assessment, estimating the likelihood that your cancer has or may spread outside the prostate and assessing your risk of disease recurrence after treatment. This assessment combined with characteristics of your overall health will allow your doctor to advise which treatment option will benefit you the most. Your doctor will use factors such as your Gleason score, PSA level, tumor stage and the number of tumor samples (called cores) taken by biopsy that are positive for cancer.

A variety of factors and tools can be used to assess your chances of surviving prostate cancer and the effectiveness of treatment in halting the progression of the disease. Among the tools your doctor may use are Internet-based calculators or nomograms, published tables and biological markers that may help predict outcomes.

Online prostate cancer calculators, also called nomograms, provide forecasts of prostate cancer outcomes by calculating the statistical probability of disease progression or patient survival after treatment by comparing your individual information to data from many hundreds or thousands of other prostate cancer patients. Two particularly comprehensive calculators are available on Web sites from Memorial Sloan Kettering Cancer Center in New York (www.nomograms.org) and the University of Montreal (www.nomogram.org) .

The advantage of these predictive tools is that they are individualized to your particular condition and characteristics. The calculators ask you to respond to questions about your PSA level, age, tumor stage, Gleason score, biopsy cores and planned treatment or other information. Calculators are available to help you and your physician make treatment decisions before and after initial treatment and after a relapse.

However, as more men are diagnosed with lower-risk disease, these nomograms are proving less useful. For those men with newly diagnosed prostate cancer the great majority will be assessed as low or intermediate risk. These nomograms provide limited information to distinguish those men whose cancers will be cured from those in whom treatment will fail. In men with low or intermediate risk disease, new approaches and technologies involving biological markers are being developed to improve your doctor’s ability to estimate the curability of the cancer (see Biological Markers below).

You should talk with your physician or medical team to help you interpret the results of these calculators and make decisions about any planned treatment. The statistics you receive by filling out these nomograms will help you have an informed discussion with your doctor.

Created in 1997 and updated in 2001, Partin tables are published tables developed by urologists at the Brady Institute for Urology at Johns Hopkins University in Baltimore. Named for the lead authors of this research, the Partin tables are based on data from patients treated at three major prostate cancer research institutions: Johns Hopkins, Baylor College of Medicine in Houston and the Michigan Prostate Institute at the University of Michigan in Ann Arbor.

Like the online calculators, the Partin tables combine data on PSA levels, Gleason score and tumor stage to predict specific treatment outcomes for an individual patient. Physicians can use the tables to calculate probability estimates of four different risk factors that are important in making treatment decisions:

• that your cancer is completely confined to the prostate;
• that you have capsular penetration, meaning that your prostate cancer has extended into and possibly through the capsule (hard outer covering) of the prostate;
• that your cancer has extended into the seminal vesicles (glands behind the prostate);
• that your prostate cancer has spread to the lymph nodes.

It’s important to understand that the value of these tables in predicting outcomes has never actually been proved, and you should discuss the value of these tables with your physician.

PSA is a widely used biological marker, or biomarker, of prostate cancer risk. A lot of research is currently being done to identify other biomarkers of risk that may enhance the predictive value of nomograms and improve a physician’s ability to predict capsular penetration and distant metastasis (spread) of prostate cancer as well as cancer recurrence after treatment.

New approaches to risk assessment for prostate cancer are also emerging that combine biomarker testing, biopsy tissue analysis and clinical data to provide personalized risk assessments that could improve the accuracy of predicting patient outcomes from cancer treatments.

Once prostate cancer has been diagnosed, it is important to find out whether or not the cancer has grown beyond the prostate. Doctors rely on the findings of imaging studies to determine the stage of disease, or how extensive the cancer has become. A widely used system helps doctors classify the stage of cancer according to such characteristics as the size and location of the tumor and the absence or presence of cancer in nearby lymph nodes or other parts of the body. This system was developed by the American Joint Committee on Cancer and is known as the tumor, node, metastasis (or TNM) classification. The stage of the prostate cancer, along with prostate-specific antigen (PSA) levels, is an important factor in planning treatment. In addition, the doctor uses the staging information to help predict the prognosis, or outcome, which also aids in selecting a treatment approach that is best for an individual man with prostate cancer.

As a first step in determining the stage of prostate cancer, the doctor who has evaluated the findings of diagnostic tests will assign a clinical stage (Table 1). This stage will be confirmed or modified by the pathologist who examines tissue removed during surgery (the pathological stage). The pathologist will also grade the tumor according to how it looks under a microscope. The grade assigned to the tumor is known as the Gleason score. The Gleason score ranges from 2 to 10; a low score is given when the tumor cells are similar to the normal cells in the prostate tissue. Higher scores are given for greater differences between the tumor cells and the normal cells. The more different the tumor cells are from normal, the more likely the tumor is to spread. Gleason scores are grouped as follows:

As the last step in determining the overall stage, the TNM classifications and the Gleason score are considered together to classify prostate cancer as stage I, II, III, or IV (Table 2). Some doctors may use an older staging system, the Whitmore-Jewett system, and assign stage A, B, C or D to the prostate cancer. Patients are encouraged to ask their doctors to explain the staging system they use or to translate the stage into a stage determined by the TNM and Gleason classifications

Table 1. TNM Classification of Prostate Cancer

*When a tumor is found during surgery not related to prostate cancer, it is further classified as T1a if tumor cells are found in 5% or less of the surgically removed prostate tissue, and as T1b if tumor cells are found in more than 5% of the surgically removed prostate tissue. A tumor is classified as T1c if it is found during a needle biopsy, usually done because of an elevated prostate-specific antigen (PSA) level.

Table 2. Stages of Prostate Cancer

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