Prostate Cancer
(Prostate Problems · Cancer of the Prostate)
In this condition factsheet:
The Facts on Prostate Cancer
Prostate cancer is the most often diagnosed cancer in Canadian men, aside from skin cancers. It ranks third as a cause of cancer death in Canadian men aged 65 and over.
As an important part of the male reproductive system, the walnut-shaped prostate gland produces liquid that moves sperm. It is located between the rectum and the pubic bone, beneath the bladder.
When the condition is found early, and if it is located only in the prostate gland, treatment of prostate cancer can be more successful. If the cancer spreads to other areas of the body, treatment may become more difficult.
Causes of Prostate Cancer
Cancer tumours grow from cells that have undergone genetic mutations. These changes cause cells to multiply at very fast rates. They eventually form a mass that keeps growing – this is called a tumour.
In some people, the genetic mutation is inherited. Some prostate cancers occur in men who have particular genetic mutations, such as genetic mutations seen in some families with breast and ovarian cancer. However, most cancer-causing genetic changes occur after birth.
Some genes don't directly cause cancer, but may make cells more vulnerable to carcinogens (cancer-causing agents) found outside the cell. Men of African descent have almost double the prostate cancer rates of Caucasians, possibly due to this factor.
Various factors can increase or reduce the chance of mutations, and therefore cancer. The following factors are believed to increase the risk of prostate cancer:
- age: Greater age, especially over 65, comes with greater risk.
- family history: Having a father or brother with prostate cancer doubles your risk (some families carry gene mutations that increase the risk of developing prostate cancer).
- race: Men of African descent are more likely to get prostate cancer and men of East Asian descent are at a lower risk.
- geography: Prostate cancer is rarer in Asia, Africa, and South America.
- weight, physical inactivity: Overweight and inactive men have higher rates of prostate cancer.
- diet: Eating high-fat foods and red meats, and not eating enough vegetables, fruits, and fibre increases your risk.
- smoking: People who smoke have a higher risk of developing prostate cancer and a poorer prognosis after diagnosis.
Diet may be a crucial factor in prostate cancer. The fact that Africans are far less affected by prostate cancer than Americans of African descent suggests that diet and lifestyle are partly to blame. Research has shown a link between high saturated-fat diets and prostate cancer. Some experts argue that a lack of fruits and vegetables is the problem, and that people with high-fat diets get more cancer because they tend not to eat enough vegetables. Along with a high-fat diet, very high calcium intake has also been linked to prostate cancer.
Some foods may protect against prostate cancer. Tomatoes, grapefruit, and watermelon all contain lycopene, a chemical that may lower risk of prostate cancer. Many studies have also suggested a protective effect for vitamins E, selenium, and cruciferous vegetables like broccoli, cauliflower, Brussels sprouts, and bok choy. If you plan on supplementing your diet with any of these nutrients, be sure to talk with your doctor or pharmacist first. For example, high doses of zinc supplements (more than 100 mg daily) may lead to an increased risk of developing the condition.
Symptoms and Complications of Prostate Cancer
Prostate tumours are usually small and cause no symptoms. That's why most of them are only discovered during blood screening tests or surgery for benign prostatic hyperplasia, which often does cause noticeable symptoms.
Large, advanced tumours can press on other organs such as the bladder, causing incontinence (reduced bladder control) or making urination difficult or painful. Problems related to urination may occur as a result of prostate cancer because the urethra (the tube that carries urine from the bladder out of the body) passes directly through the prostate gland. These tumours may also interfere with the nerves responsible for erection of the penis, which leads to erectile dysfunction.
Advanced tumours can also cause:
- pain by pressing on the spine or pelvis
- burning or pain when urinating
- frequent urination
- pain when ejaculating
- blood to appear in the urine or semen
- pain or stiffness in the lower back, hips, or upper thighs
If cells from a tumour break off and move into the bloodstream, they can settle in distant parts of the body and start dividing to form new tumours. This process of migration is called metastasis, and the new tumours are called metastases. You may suffer pain in distant parts of the body if the cancer has metastasized.
As well as travelling by blood, loose cancerous cells can be carried through the lymphatic system, which is a network of tubes that carry lymph (a clear liquid containing waste products and immune cells). From there, it can spread to various lymph nodes and other organs. The lymphatic system is the main carrier of metastases in prostate cancer. Secondary tumours can grow almost anywhere in the body, such as the lungs, brain, lymph nodes, however, it is most likely to spread to the bone.
