Providence Prostate Cancer Evaluation
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Tumor Factors Partin Evaluation Risk Category Summary
Tumor Factors Defining the Extent and Severity of Cancer
There are three measures used to determine the extent and severity of cancer. These measures are Grade, Stage, and PSA.
Grade (Gleason Score)
Grade is a means of describing the aggressive behavior of a cancer. Low-grade tumors tend to grow slowly and tend to remain in or around the prostate. High-grade tumors tend to grow quickly and are more likely to spread beyond the prostate. How is grade determined? A biopsy of the tumor is performed. A pathologist will then evaluate this biopsy by determining the growth pattern and appearance of the malignant cells under the microscope. Based on their growth pattern, the sample will be given a grade on a scale of 1 to 5. Grade 1 cell growth is nearly normal; grade 5 cell growth is the most abnormal.
Gleason Grades from 1-5
Tumors often exhibit more than one pattern of cell growth. To account for this, a Gleason Score is calculated. To determine a Gleason Score, two cell growth patterns will be graded. The sum of these grades is known as a Gleason Score.
A high Gleason Score does not mean that the cancer has spread. It only predicts the likelihood of the cancer spreading.
Stage is a term used to define the size and scope of a cancer. The goal is to diagnose the cancer as early as possible, before it has spread beyond the prostate region. Stage is determined by Digital Rectal Exam (DRE), radiological studies (X-rays, CAT scans, bone scans), and pathology (inspection of tumor specimens under a microscope after surgery).
Stage T1: The tumor cannot be felt. Stage T1a and T1b tumors are diagnosed after surgery to improve urine flow. The part of the prostate removed is found to contain cancer. T1c tumors are usually diagnosed because the PSA is elevated, prompting a biopsy.
T2 tumors can be felt, but are confined to the prostate gland. T2a tumors involve less than one half of one lobe of the prostate. T2b tumors involve more than one half of one lobe. T2c tumors involve both lobes.
T3 tumors extend beyond the prostate gland. T3a tumors extend beyond the prostate capsule. T3b tumors extend into the seminal vesicle. Patients who are found to have disease beyond the prostate after surgery are said to have “surgical T3 disease “ or “pathologic T3 disease”.
In summary: Stage is what the doctor feels (DRE), or sees (scans). It tells us how far along the growth pathway the cancer has progressed.
Prostate-Specific Antigen (PSA) Level
The final factor in determining the extent of prostate cancer is the serum Prostate-Specific Antigen (PSA) level. PSA is a naturally occurring substance that is released in the bloodstream. Normal prostate cells and prostate cancer cells produce it. The PSA level tells doctors two things about the prostate cancer:
- How much cancer is present
- How fast the cancer growing (requires more than one PSA value)
A higher PSA level usually indicates a greater amount of prostate cancer. A doubling of a PSA level in less than six months represents rapid cancer growth. Some say that the PSA level is more accurate than stage in determining how far the cancer has advanced. In fact stage and PSA complement one another. A man may have early Stage disease but have a high PSA , suggesting more disease is present than indicated by the Stage. On the other hand some men have a low PSA but a more advanced Stage, suggesting there is more disease present than the PSA suggests.
Combining Grade, Stage, and PSA Factors: The Partin Method
The Partin Table was generated by studying hundreds of men who underwent surgery. Dr. Partin, a urologist, studied the location and extent of cancer after surgery . The extent (location) of disease was mapped for men with similar Grade (Gleason Score), Stage, and PSA level before surgery. For example, if 100 men underwent surgery with the same factors, where was the cancer actually located?
Partin Tables are available on this web site to calculate the likely location of your prostate cancer. The three factors—Grade, Stage, and PSA are used to predict the possible locations of the cancer. There are four possibilities. One is that the disease is confined to the prostate. The second is that there is capsule penetration or extension beyond the capsule. Third is the possibility that the tumor extends outside the prostate into a local organ called the seminal vesicle. Finally, there is a chance of lymph node involvement or spread to the lymph nodes near the prostate gland.
Consider the following example: A man has a Gleason Score of 7 (4+3), a stage of T2a, and a PSA level of 5.6. The chance that an individual with these numbers has disease confined to the prostate is 33%. The chance that there is disease beyond the prostate and through the capsule is 56%, the chance of seminal vesicle involvement is 5%, and the chance of lymph node involvement is 6%.
The Partin Table summary can be very helpful in choice of therapy. For the individual above with a Gleason 7, T2a,PSA 5.6 cancer treatment must be designed to cover all possibilities. Such a person might be inclined to combined modality therapy - external beam therapy plus implant therapy, since external beam therapy results in a wider area of coverage. However, someone with an 80% chance that the disease is confined to the prostate may consider implant therapy alone as the appropriate option.
Even with the Partin Table information, there is great controversy about how to decide between implant therapy alone and external beam therapy combined with implant therapy (combined modality therapy). At our institutions, implant therapy alone is reserved for men with a relatively high chance that the disease is confined within the prostate or just beyond the prostate (capsule penetration). Men who have a higher chance of disease beyond the prostate are treated with a combination of external beam and implant therapy. There are no absolute rules in this regard, however, and for all individuals with prostate cancer, an argument for implant alone or combination therapy can be made. Excellent alternative to implant therapy is external beam therapy alone.
Combining Grade, Stage, and PSA Factors - The Risk Category Approach
A simpler way to categorize prostate cancer is to divide men with prostate cancer into three risk categories. This has proven useful in comparing results of surgery, radiation therapy, and implant therapy. In this scheme, Grade, Stage, and PSA level are combined to produce a risk rating. The three categories are:
Low Risk (Clinical Stage T1c or T2a, PSA level <10 ng/mL, Gleason Score of 6 or less)
Intermediate Risk (Clinical Stage T2b, PSA 10 to 20 ng/mL, Gleason Score of 7)
High Risk (Clinical Stage T2c, PSA >20 ng/mL, Gleason Score of 8 or higher)
It must be noted that this is one of many schemes to categorize prostate cancer. It is useful in its simplicity, but within each category, there is a wide range of prostate cancer severity. Also, the term high risk tends to be inflammatory and frightening rather than helpful. In fact, all degrees of prostate cancer (low, intermediate, and high risk) are potentially curable. The risk category merely helps in attempting to create the most effective treatment program.
This has been a review of permanent prostate implant radiation therapy. Many other excellent and proven options are available for the treatment of prostate cancer, including surgery and external beam radiation therapy alone. As techniques improve, the cure rates with all the therapies have improved. In addition, the side effects of all therapies have improved, especially implant therapy.
The final decision about the appropriate therapy depends on individuals understanding their disease, knowing very clearly what their priorities are (cure rate vs. quality of life considerations), and intuition. For many men, within five minutes of hearing the diagnosis of cancer, they know exactly what treatment option they will or will not pursue. For others, it is a great struggle to consider all of the various factors and choose the best therapy for them. This has been an attempt to accurately and fairly present the implant therapy option in its complexity, to allow fair and reasonable consideration of this option.
Nothing can replace the direct discussion between a man and his experienced oncologist in making the final treatment decision.
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For many men, the risk category is more useful than the Partin Table. With regard to implant therapy, men with low-risk disease are candidates for implant therapy alone or implant therapy in combination with external beam therapy. Intermediate-risk patients are also candidates for implant therapy alone, but we tend to favor external beam therapy plus implant therapy due to the slightly higher risk of disease beyond the prostate. Finally, for high-risk individuals, we favor external beam therapy in combination with implant therapy. The meaning of low risk, intermediate risk, and high risk is summarized as: