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.

Doctors use staging information to plan treatment and to help predict the prognosis, or the likely outcome after therapy. Outcome may be defined in various ways, such as 5-year survival or 5-year survival without any evidence of prostate cancer. Having an estimate of prognosis allows the physician and the patient to select a treatment approach that is best for an individual man.

The Tumor, Node, Metastasis (TNM) classification developed by the American Joint Committee on Cancer (AJCC) is used to stage prostate cancer. As a first step in identifying the stage of disease, the doctor who has evaluated the findings of diagnostic tests will assign a clinical stage. Clinical stage is defined on the basis of the evaluation of a biopsy sample, the findings on physical examination and the results of imaging studies, which usually include a bone scan and computerized tomography (CT). These tests enable the doctor to estimate the size and location of the tumor (T category) and the absence or presence of cancer in nearby lymph nodes (N category) or other parts of the body (M category) (Table 1).

The pathologist will also examine a sample from the prostate biopsy under the microscope and assign a grade to the tumor. With this grade, classified for prostate cancer using the Gleason system, the pathologist assigns a total Gleason score, which ranges from 2 to 10. A low score is given when the tumor looks more like normal prostate tissue, and higher scores are given when the cancer looks “less differentiated” or less like normal tissue. The higher the Gleason score, the less differentiated or more different from normal the tumor appears. The higher the Gleason score, the more likely the tumor is to spread. The Gleason score became a factor in the AJCC staging system when the system was updated in 2009. Another factor added in that update is the preoperative prostate-specific antigen (PSA) level. The Gleason score and PSA level were added because studies had found that outcomes varied according to these factors.

Stage may be confirmed more precisely by examining tissue removed during surgery (this stage defined by surgical removal of tissue is called the pathologic stage).

The AJCC classification is then used to determine an overall stage of disease (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 AJCC system, as the AJCC system has been shown to provide much more prognostic information.

*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.

*The prostate cancer is defined as stage I when the Gleason score and PSA level are not known for men who have a tumor with either of these TNM classifications.

?The prostate cancer is defined as stage IIA when the Gleason score and PSA level are not known for men who have a tumor with either of these TNM classifications.

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