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Early detection of prostate cancer

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Introduction to prostate cancer

Early detection of prostate cancerThe prostate is a gland of the male reproductive system, sitting at the base of the bladder and surrounding the urethra. Cells of the prostate can become cancerous; 95% of prostate cancers are adenocarcinomas (tumours which develop in glandular tissue) but can rarely be neuroendocrine carcinomas (tumours that develop from cells that secrete hormones or are associated with the nervous/hormonal system).

Prostate cancer is the fifth most common cancer in the world and Australia is among the countries with the highest rate (105 cases per 100,000 males). To age 85, 1 in 4 Australian men will be diagnosed with prostate cancer and 1 in 25 will die from it, making it the second leading cause of cancer death.

While a common disease, many prostate cancers are very slow-growing and may never cause clinical symptoms or metastasise. Most men with prostate cancer are more likely to die of something else.

Male urogenital systemFor more information on the prostate, see Male Reproductive System.

 

Prostate cancer typesFor more information about prostate cancer, see Prostate Cancer Overview.

 

Risk factors for prostate cancer

While a very common disease, certain risk factors for prostate cancer have been identified. In some instances, these risk factors are hereditary and cannot be modified.

  • Age – Men have a risk of prostate cancer of 1 in 7 before the age of 75 and 1 in 4 before the age of 85;
  • Race – African Americans are at greater risk of prostate cancer; and
  • Smoking – Significantly increased risk of prostate cancer in current and former smokers, and of fatal prostate cancer in current smokers.

 

Other factors have been identified as posing a possible increased risk of prostate cancer. This includes a family history of prostate cancer, a history of sexually transmitted infections and possible associations with certain diets, such as high intakes of dairy protein, polyunsaturated fats, folic acid and preserved foods. Several genes have also been identified as increasing the risk of prostate cancer in certain men. At this stage, the best lifestyle advice for reducing prostate cancer risk is smoking cessation and a healthy, balanced diet.

There is no evidence to suggest that a vasectomy increases the risk of prostate cancer, and alcohol has not shown consistent affects on rates of prostate cancer. High ejaculation frequency and childlessness have been shown to decrease the risk of prostate cancer.

Screening for prostate cancer

Early detection of prostate cancerAustralia has the highest incidence of prostate cancer in the world and 1 in 25 Australian men will die from it. Consequently, there has been significant debate in the past few decades (particularly since the discovery of prostate specific antigen (PSA) testing) over the use of population screening programmes for prostate cancer.

There is not enough evidence currently to support screening men with no symptoms of prostate cancer. While early detection of prostate cancer is advantageous, screening has not been shown to reduce mortality (death) or improve outcomes. There is also the risk of harm from further investigations, complications of treatment and psychological stress of “false positive” (a positive test result from a man without prostate cancer) test results.

Australian guidelines recommend investigating for prostate cancer on a “case by case” basis with discussion of risks, benefits and alternatives. It is advised that men consider getting tested for prostate cancer from age 50. Men with significant risk factors for prostate cancer may require screening from age 40–45. Men wishing to be screened for prostate cancer should see their general practitioner.


Digital rectal examination (DRE)
A digital rectal examination (DRE) is an important part of a thorough clinical examination. It takes only a few minutes to perform and allows the doctor or nurse to examine the rectum and nearby organs, such as the prostate gland, bladder and perineum. It is performed by gentle insertion of a well-lubricated finger into the anal canal. While it can be briefly uncomfortable, a DRE is critical in examining a man for prostate cancer. The prostate is normally firm and smooth and any cancerous change in the prostate can feel like hard or irregular changes to the prostate tissue. The DRE is usually used in combination with a PSA blood test in screening. A DRE combined with PSA test is the most accurate screening test for prostate cancer, better than using PSA or DRE alone.


Prostate specific antigen test (PSA)
Prostate specific antigen (PSA) is a protein that is produced by the cells of the prostate gland and can be detected by a simple blood test. PSA has been shown to be elevated 5–10 years prior to clinically evident prostate cancer.The use of PSA as a screening tool for prostate cancer became common in the 1990s, leading to a significant increase in the incidence of diagnosed prostate cancer.

However, the PSA is not a perfect test. An elevated PSA does not necessarily mean a man has prostate cancer. These “false positives” can lead to further investigations, the risk of complications and unnecessary psychological stress. Similarly, not all prostate cancers cause a rise in PSA. These “false-negative” PSA results can miss early, aggressive or treatable cases of prostate cancer. It also remains unclear exactly how well PSA correlates to low and high-risk prostate cancers.

The Cancer Council of Australia does not recommend the use of PSA for screening of prostate cancer in men without symptoms, given the lack of evidence that benefit outweighs risk.It is important for men and doctors to discuss these risks and benefits on an individual, case-by-case basis.


Other options

Population-level screening of all asymptomatic men with DRE and PSA (alone or in combination) for prostate cancer is not advised. Guidelines recommend screening for prostate cancer on a case-by-case consideration, from age 50 in low risk men. Men with additional risk factors may commence screening as early as 40–45 years old.

To make an informed decision, doctors should clearly explain the risks and benefits of DRE, PSA and screening for prostate cancer. Different men, depending on their medical and family history, will need individual consideration of their risk factors and the benefits of screening.

You should report any new or changing urological symptoms to your doctor, such as difficulty with urination or changes in normal urinary function. These symptoms can represent changes in the prostate tissue that will require further investigation for prostate cancer.

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Dates

Posted On: 28 December, 2005
Modified On: 10 August, 2012
Reviewed On: 9 August, 2012

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