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Cancer Staging: An Educated Guess From the book Prostate cancer goes through three phases: Initially, one or more normal cells within the prostate gland transform into cancer cells. These cancer cells then multiply inside the prostate, but remain enclosed by a thin wall around the prostate called the capsule. In the second phase, cancer cells inside the prostate penetrate the capsule of the prostate and spread into the surrounding organs: the rectum, bladder, sphincter muscles, sex nerves, and seminal vesicles. (These cancer cells, called microscopic capsule-penetration cancer cells, can be discovered with a microscope only after radical prostatectomy.) Microscopic capsule-penetration cancer cells then spread (i.e. metastasize) through the lymphatic system and blood vessels into lymph nodes, bone and throughout a man's body. In order to treat a man diagnosed with prostate cancer, the doctor must first find out where the cancer cells are located. Obviously, the prostate biopsy indicates that there are cancer cells inside the prostate. The big question is whether the cancer cells have penetrated the capsule and whether they have metastasized. Manual examination of the prostate (the DRE), and at times CT scans, MRI scans, and ProstaScint scans are performed to try to determine whether the cancer has penetrated the prostate capsule. To check for metastasis, a bone scan may be performed. Occasionally, pelvic lymph nodes may be removed by a surgical procedure called a pelvic node dissection. However, most men diagnosed today do not need these procedures because the chance of finding metastases is so slim. To indicate where prostate cancer cells are located, a staging system was devised. When men are believed to have cancer only in the prostate gland, we classify them as having stage T1 or stage T2 prostate cancer. If it is known before treatment that cancer cells have penetrated the capsule, men are classified stage T3. Today, almost al men are classified stage T1 or T2. Few men are classified before treatment as stage T3. However, the staging system is highly inaccurate. When a patient is classified with stage T1 or T2 prostate cancer, this means that the doctor is just guessing that the cancer has not penetrated the capsule. Unfortunately, doctors often guess wrong. In fact, they guess wrong 50 percent of the time. Even with the digital exam. CAT scans, MRI scans and ProstaScint. scans, there is absolutely no way to know or sure whether prostate cancer cells have spread beyond the capsule and spread into the adjacent bladder, rectum, or sphincter muscles. How inaccurately doctors determine staging before treatment can be seen from the Partin Tables. The Partin Tables were compiled from patients who had a radical prostatectomy for what was thought to be stage T1 and T2 cancer. After surgery, the entire prostate specimen was carefully examined under a microscope by pathologists. They found that at least 50% of the men actually had cancer that had penetrated the prostate capsule and spread into the surrounding organs. These men were then classified as stage T3. However, even the Partin Tables are not perfect. Up to 15 to 20 percent of men with cancer cells determined microscopically to be only in the prostate (i.e.,organ-confined) fail to be cured by radical prostatectomy. Thus these patients had capsule penetration that could not be found even with microscopic examination of the entire prostate. So even if we could examine the prostate under a microscope before treatment, we would be guessing wrong about capsule penetration up to 20 percent of the time. Although the Partin Tables are not perfect, they are still the best way to determine the chance of capsule penetration. The chance that cancer cells have penetrated the capsule and gone into the surrounding organs is related to the PSA level before treatment, as shown in Table 1. Using this summary of the Partin Tables, you can see how often doctors guess incorrectly about where cancer cells are locate. Even 25 percent of patients with what we think to be very early prostate cancer--those with a pre-treatment PSA level of 4.0 ng/ml or less--actually have cancer cells that have penetrated the prostate capsule. This information is important to any patient newly diagnosed with prostate cancer because cells will be missed and therefore not treated if doctors guess wrong about cancer-cell location. Under treatment of prostate cancer is one of the worst things a doctor can do. Table 1
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