Answers to Common Questions About PSA Testing
This information is an adapted version of a medical journal article written by William J. Catalona, MD; Misop Han, MD; and Stacy Loeb, MD. Should Screening for Prostate Cancer Begin Before 50 years old?
We, as well as the National Comprehensive Cancer Network, recommend a baseline PSA test for all men at age 40 years to assess their risk for prostate cancer.
A relevant study (Whittemore) reported that PSA levels in young adulthood are useful predictors of prostate cancer detection many years later.
In our PSA screening study, the baseline PSA level for men in their 40s was a stronger independent predictor of prostate cancer risk than ethnicity, family history, or digital prostate examination findings
The value of annual PSA testing for men in their 40s is that changes in PSA level over time (PSA velocity) can be used to help guide a recommendation for biopsy.
Another reason to begin screening men at a young age is evidence suggesting an excellent outcome for treatment in this age group. In a randomized clinical trial of radical prostatectomy versus watchful waiting (Bill-Axelson), men younger than age 65 years had the largest survival advantage with radical prostatectomy.
Furthermore, younger men are less likely to experience impotence and incontinence after surgery.
Should a PSA Value Below 4.0 Trigger a Biopsy?
The 4.0 ng/mL PSA threshold for prostate biopsy misses a substantial proportion of prostate cancer cases at PSA levels less than 4.
When PSA 4 is used for recommending biopsy, approximately one third of tumors have already spread to the margins of the prostate gland or beyond . Overall, prostate cancer was detected in 15.2% of men with total PSA levels less than 4.
As a result, beginning in 1995, William J. Catalona, MD lowered the PSA
threshold for biopsy in his research studies and in his clinical practice to
2.5 ng/mL for men of all ages. Many urologists now follow this recommendation.
The use of a lower PSA threshold immediately increases the number of prostate biopsies performed; however, many of these biopsies would ultimately be performed for a higher PSA level anyway. The lower PSA threshold merely allows them to be performed sooner.
In addition, the number of unnecessary biopsies in men without prostate cancer can be reduced through the informed use of the PSA test and other PSA factors such as PSA velocity, PSA density and percent freePSA.
Prostate cancer screening should avoid detecting cancer so early that diagnosis and treatment of “harmless cancer” cause unnecessary medical complications.
We found that prostate cancer detected at a PSA level of 2.6 to 4.0 is statistically significantly more likely to be organ-confined than cancer detected at a PSA level of 4.1 to 10. And, it is not more likely to meet criteria for “insignificant” disease.
In a recent update of our early studies, we found that when we used 2.5 as the threshold for biopsy, fewer than 10% of cancer cases were “insignificant” at any time interval during the 12-year study period.
Another study in Austria (Pelzer) validated our findings. Compared with cancer detected in patients with PSA levels of 4 to 10, cancer detected at lower PSA levels was statistically significantly more likely to occur at earlier stages and in younger patients, that is, in optimal candidates for treatment with good potential for cure.
Furthermore, we recently reported that 10- year progression-free survival following radical prostatectomy is statistically significantly higher in men with a preoperative PSA level of 2.6 to 4 than in men with higher PSA levels.
Should Screening for Prostate Cancer Stop at 70 to75 years old?
The American Cancer Society currently recommends that prostate cancer screening be offered only to men with a life expectancy greater than 10 years because as the risk for death from competing causes increases, the benefits of screening decrease.
According to information in the U.S. Life Tables, the average life expectancy is 13 years for a 70-year-old man and is 10 years for a 75-year-old man. Thus, screening is appropriate for some men older than age 70 years.
Nevertheless, it is difficult to make categorical recommendations for such a diverse population. Clearly, elderly men with other serious medical conditions, and a correspondingly shorter life expectancy, usually have little to gain.
Many elderly patients request prostate cancer screening, and it is difficult to deny it merely because of their age. All patients should be counseled about the potential risks and benefits of screening, and physicians should then respect their wishes.
A recommendation for screening does not mean that every 70 to 75 year old man with abnormal screening test results should undergo immediate biopsy or that every patient with prostate cancer must be treated immediately and aggressively. Nevertheless, for those who choose biopsy, it can be performed with minimal discomfort and risk in an outpatient setting, and for those who desire treatment, various options are available, each with specific advantages and disadvantages.
And for men who have clinically localized prostate cancer with favorable clinical and pathologic features suggesting low risk for progression and are managed with active monitoring, the knowledge of a cancer diagnosis may increase the vigilance of their physicians, enabling treatment to be instituted promptly if there is evidence of cancer progression.
Men older than age 70 years who are in good health may continue to benefit from screening and should be given the opportunity for prostate cancer detection at a stage when cure is possible.
