Prostate Cancer Stages
Like all forms of cancer, the prognosis for prostate cancer depends on how large the tumor is and how far the cancer has spread at the time of diagnosis. The diagnosis is made from the results of laboratory analysis, and by other means like x-rays. Doctors take this information and use a standardized system of classification called stages. There are four stages which classify prostate cancer by judging things like how big the tumor is, how far it has spread, into which organs or tissues it has spread, and how advanced is the cancer.
Cancer sometimes grows in a man’s prostate gland for many years, but so slowly that it is not a health risk. It is only when the tumor becomes large, or when the cancer grows beyond the prostate gland that it becomes dangerous. The cancer can grow beyond the prostate in three different ways. It can grow into neighboring tissues; this is called invasion. It can grow into the lymphatic system, the lymph vessels and the lymph nodes. Last, it can spread through the circulatory system and get into other tissues even if they are far away from the prostate. This is called metastasis and is when cancer that starts in the prostate can be found in other places like the bones, the lungs, or the brain.
The staging classification system most often used by doctors is the TNM system. The letters in the system are used to denote the cancer stage. The letter “T” is used to signify tumor; the letter “N” is used to signify lymph nodes; and “M” is used to signify metastasis. The T stage is the least advanced, the N stage indicates middle advancement, and the M stage indicates a late stage, or more advanced cancer.
Within each of these stages (T, N, and M), there are categories and sub-categories which indicate the precise advancement of the cancer.
In stage T, there are four main categories and many sub-categories. These are the main categories: TX – the primary tumor is too small to be seen or assessed; T0 – there is no evidence of a primary tumor; T1 – the primary tumor cannot be found by physical examination, or by the use of scans, but was found accidentally during a surgery for other reasons; T2 – the tumor is found only within the prostate itself; T3 – the tumor has extended through the prostate and into nearby tissues; T4 – the tumor has extended beyond the prostate and has been found in other organ structure such as the rectum, the pelvic wall and the bladder.
In stage N, there are three main categories. These categories are: NX – the lymph nodes could not be assessed; N0 – the lymph nodes do not show any evidence of cancer; N1 – the lymph nodes show evidence of cancer.
In stage M, there are three categories. These categories are: MX – the presence of metastases could not be assessed; M0 – there is no evidence of metastasis; M1 – there is evidence of metastasis.
Another system used to classify prostate cancer is called the Jewett system. It uses the letter A through D to signify the various stages. The letter A is used to indicate the least advanced forms of cancer; the letters B and C are used to designate middle advanced forms of cancer; and the letter D designates the most advance form of cancer. These stages generally correspond to the TNM stages mentioned before.
There is one other system used to classify cancer called the Gleason system. This system examines the cancer cells under a microscope to determine if the type of cancer present is very aggressive and is a kind which can grow quickly, or if the cancer is less aggressive and slow growing. This system grades the cancer from 1-5.
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