The assignment of patients to a given risk category is generally a function of three principal diagnostic measures used in the field of prostate cancer: stage, grade, and PSA.

     Stage: Tumor stage refers to the size of the cancer in the prostate and whether or not tests have shown it to have spread beyond the gland. This is a critical factor in selecting an appropriate treatment option and assessing a patient‘s prospects for long-term survival. Stage is determined by physical examination, including a digital rectal exam and, if needed, an ultrasound exam. Other diagnostic tests, such as a biopsy or bone scan, or MRI can also be used.

     Under the commonly used TNM (Tumor, Nodes, Metastasis) staging system, tumor stage is denoted by a "T" value that ranges from 1- 4 with alphabetic subcategories (e.g., T2a) that further refine the description of the tumor. Stages T1 and T2 indicates early stage disease, that is, cancer that appears to be confined to the prostate. These are the patients who are candidates for any local treatment intended to cure the cancer, be it surgery, external beam radiation, or seed implantation.
 
     Grade: The grade of a cancer is an estimate of how aggressively, or fast, the tumor cells are growing. It is based on a pathologist’s examination of the cancer cells found in the tissue samples taken in the biopsy that confirmed the presence of cancer. The grade (or Gleason score named after the physician who developed the system) ranges in value from 2 to 10. The higher the score, the greater the likelihood that the tumor cells will grow quickly and the greater the chance that the cancer will have spread beyond the prostate at the time of diagnosis.

     PSA: Found in the blood, PSA (prostate specific antigen) is a substance produced by both normal and cancerous prostate cells. The higher the PSA level, the greater the concern over the possible spread of the cancer. A PSA level less than 10 is usually more reassuring while levels above 20 are more worrisome.
 
     Taken separately, each of these measurements has its own limitations. Taken together, and combined with other pertinent information, these three key indicators give physicians the best opportunity to arrive at an accurate estimate of whether or not cancer is confined to the prostate gland.

     Before leaving the topic of risk, it is important to clarify the significance of capsular penetration. The term means that cancer cells have extended into, and possibly through, the prostate capsule, the layer of fibrous tissue that forms the outer lining of the prostate.

     On the basis of inquiries at SPI, and presumably elsewhere, a number of patients appear to believe that once any cancer cells have spread beyond the prostate capsule, all hope of cure, or long term disease-free survival, is lost. This is a mistaken belief. On the contrary, considerable research based on radical prostatectomy tissue samples has shown that in the majority of cases in which capsular penetration has occurred, the cancer cells are found only within a few millimeters of the prostate. At this short distance, the cells are well within the extra layer of surrounding tissue that is removed during radical surgery (the surgical margin) or within the radiation field covered by a seed implant (the target volume).