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What is the prostate?
The prostate is a male organ that lies below the bladder (See Figure 1). It is relevant because :
- It is a gland, meaning it secretes fluid. About 30% of semen is secreted by cells within the prostate. These secretions are necessary for fertility.
- The rest of semen, including the sperm, also travels through the prostate during ejaculation.
- Urine exits the bladder via the urethra–a tube going from the bladder to the tip of the penis. Part of the urethra travels through the prostate.
- Nerves that contribute to erections and continence (keeping urine from leaking) travel alongside the prostate.
What is prostate cancer?
Prostate cancer generally refers to a cancerous process occurring in the glands of the prostate. The following is an explanation of the full course of this cancerous process. Whether or not the initial cancer progresses along this course depends on several factors. Please see the diagnosis section for the factors that affect cancer progression.
- The cancerous process starts when a single cell acquires the ability to copy itself without restrictions that usually control copying. This group of copied cells forms a lump called a tumor. This tumor stays confined within the prostate at first. This is referred to as localized prostate cancer.
- This tumor eventually grows larger than the prostate and invades areas around the prostate. This includes the bladder, seminal vesicles, rectum, muscle and fat (See Figure 1). This is referred to as locally advanced prostate cancer or locally invasive prostate cancer.
- Eventually, cancer cells may also spread beyond the local area of the prostate. This spread occurs via the two networks of fluids that exist in the body-the blood and the lymph. Via these networks, prostate cancer may spread to lymph nodes or other organs, most commonly the bone in the case of prostate cancer. This process is called metastasis. This type of prostate cancer is metastatic prostate cancer.
Who gets prostate cancer?
Prostate cancer is the most common cancer in Canadian men [CCS]. Only men have a prostate and thus only men get prostate cancer. In 2010, 24600 cases of prostate cancer were diagnosed and 4300 Canadian men died of prostate cancer. The Canadian Cancer Society reports that the lifetime risk of developing prostate cancer is 1 in 7 and 1 in 27 men will die of the disease. The number of men with undetected prostate cancer that will cause them no problems is undoubtedly much higher.
What causes prostate cancer?
Prostate cancer arises when changes in a cell’s DNA (mutations) allow it to enter the cancerous process described above. Additional mutations then allow cancer to progress along the cancerous process.
These mutations may be created or helped by various factors. These factors include:
- Age is the most important risk factor for prostate cancer . A diagnosis of prostate cancer rarely occurs before the age of 40 and new cases are usually diagnosed in the 60s .
- African heritage is a significant risk factor for developing prostate cancer .
- A susceptible genetic makeup is a risk factor for prostate cancer. This is suggested when a patient has had multiple family members who have had prostate cancer . Risk is increased by the number of family members with prostate cancer and an earlier age at diagnosis.
Additional web resources reviewed by us
1. Guyton, A.C. and J.E. Hall, Textbook of medical physiology. 11th ed. 2006, Philadelphia: Elsevier Saunders. xxxv, 1116 p.
2. Delongchamps, N.B., A. Singh, and G.P. Haas, The role of prevalence in the diagnosis of prostate cancer. Cancer Control, 2006. 13(3): p. 158-68.
3. Hankey, B.F., et al., Cancer surveillance series: interpreting trends in prostate cancer–part I: Evidence of the effects of screening in recent prostate cancer incidence, mortality, and survival rates. J Natl Cancer Inst, 1999. 91(12): p. 1017-24.
4. Platz, E.A., et al., Racial variation in prostate cancer incidence and in hormonal system markers among male health professionals. J Natl Cancer Inst, 2000. 92(24): p. 2009-17.
5. Zeegers, M.P., A. Jellema, and H. Ostrer, Empiric risk of prostate carcinoma for relatives of patients with prostate carcinoma: a meta-analysis. Cancer, 2003. 97(8): p. 1894-903.