Screening for Prostate Cancer with PSA

The use of PSA for screening or testing for prostate cancer is a contentious issue, and has been debated very intensely over the past couple of years. There is no firm consensus, and the field is in flux as data matures from randomised studies.

The American Urological Association has recently published its updated guidelines for ‘screening’ (testing) with PSA. Whilst these are just guidelines, and not Australia-based, they do have some strengths, and can help guide discussion with patients about the utility of PSA testing.

Not mentioned in these guidelines is emerging evidence that a single PSA test in men around the age of 40 yr may indicate future risk of prostate cancer, and thus the need (or lack of need) for PSA testing over the following 15 years, as well as possible frequency of testing.

Men under 40 years old

The Panel recommends against PSA screening in men under age 40 years. (Recommendation; Evidence Strength Grade C)

In this age group there is a low prevalence of clinically detectable prostate cancer, no evidence demonstrating benefit of screening and likely the same harms of screening as in other age groups.

Men aged 40 to 54 – at average risk of prostate cancer

The Panel does not recommend routine screening in men between ages 40 to 54 years at average risk. (Recommendation; Evidence Strength Grade C)

Men aged 40 to 54 – at higher risk of prostate cancer

For men younger than age 55 years at higher risk (e.g. positive family history or African American race), decisions regarding prostate cancer screening should be individualized.

Men aged 55-69 (this group may have the greatest benefit from screening

For men ages 55 to 69 years the Panel recognizes that the decision to undergo PSA screening involves weighing the benefits of preventing prostate cancer mortality in 1 man for every 1,000 men screened over a decade against the known potential harms associated with screening and treatment. For this reason, the Panel strongly recommends shared decision-making for men age 55 to 69 years that are considering PSA screening, and proceeding based on a man’s values and preferences. (Standard; Evidence Strength Grade B)

The greatest benefit of screening appears to be in men ages 55 to 69 years.

To reduce the harms of screening, a routine screening interval of two years or more may be preferred over annual screening in those men who have participated in shared decision-making and decided on screening. As compared to annual screening, it is expected that screening intervals of two years preserve the majority of the benefits and reduce overdiagnosis and false positives. (Option; Evidence Strength Grade C)

Additionally, intervals for rescreening can be individualized by a baseline PSA level.

Men over 70 years old

The Panel does not recommend routine PSA screening in men over age 70 years or any man with less than a 10 to 15 year life expectancy. (Recommendation; Evidence Strength Grade C)

Some men over age 70 years who are in excellent health may benefit from prostate cancer screening.

Helping Patients with PSA Decisions

Background

Prostate cancer is common. Most men will develop prostate cancer if they live long enough. Despite this, only about 3% of all men will die of prostate cancer.
This indicates that most prostate cancers do not cause trouble in a man's lifetime ('low-risk' or 'indolent' cancers). However, there are some more aggressive cancers that can cause trouble, and these benefit from detection and treatment.
Screening studies do show that the number of prostate cancer deaths can be reduced by screening with PSA. However, quite a large number of men need to be diagnosed by screening and treated to prevent one prostate cancer death.
One study (the Goteborg study) showed that 12 men need to be diagnosed to prevent one prostate cancer death. That means that 11 men were unnecessarily diagnosed. Another larger study demonstrated that (ERSPC) that 781 men need to be screened and 27 men need to be diagnosed to prevent one prostate cancer death. Thus 26 men are unnecessarily diagnosed.
Screening will detect many of these indolent cancers, and if they are detected, they may go on to be treated, perhaps unnecessarily.
Treatment is associated with long term complications in men, such as incontinence, erectile dysfunction (impotence) and bowel problems. Therefore, some men (indolent cancers that are treated) may have unnecessary treatment and suffer side effects.

The aim of screening

The aim of screening should be to identify aggressive or high-risk prostate cancers early, before they have spread beyond the prostate.
Some men are at higher risk of aggressive prostate cancer than others. These are men with a family history of prostate cancer, or with a strong family history of breast or ovarian cancer in females of the family, men of African-American decent, and men who have been exposed to some environmental agents (fire-fighters possibly, and veterans exposed to Agent Orange).
Most prostate cancers found by screening are low risk and do not need to be treated, and can just be closely followed by active surveillance.
If you choose to be screened, there is a reasonable chance you will be diagnosed with low-risk prostate cancer, and may be in a position where you have to consider treatment that may be unnecessary.

Your decision to be screened – what sort of person are you?

If you have risk factors for prostate cancer (see above), your risk of prostate cancer may be higher than the general population, and this may impact your decision to be screened.

If you are the sort of person who would be uncomfortable not being treated if low risk prostate cancer was discovered, screening may not be the right decision for you.

If you are the sort of person who would accept treatment for aggressive prostate cancer, but would be happy to observe (active surveillance) things if you just had low risk prostate cancer, then you may be a good candidate for screening.