THE "NEW" PROSTATE CANCER INFOLINK

A new paper in the Journal of Urology represents an initial attempt, based on a prospective, multi-ethnic cohort of nearly 3,000 men, to determine whether baseline PSA levels can predict, with a high level of reliability, subsequent risk for and consequential diagnosis of prostate cancer.

Between 2000 and 2012, Gelfond et al. recruited a total of 2,923 men who were all prostate cancer-free at the time of their recruitment. All men were given a baseline PSA test and evaluated for their risk of prostate cancer based on that baseline PSA level as well as such other factors as age, ethnicity, and family history of prostate cancer.

The patients were then followed for a median of 7.5 years (range, 1 month to 12.4 years). All men were seen annually for PSA testing and DRE during the course of the study, with an average of about six visits per participant. After 2011, subjects were followed with PSA only and those with PSA level of < 1.0 ng/ml were seen biannually.

Here is a summary of the core results:

• 289/2,923 men (9.9 percent) were diagnosed with prostate cancer during the follow-up period.
• The average (mean ± standard deviation) age of the patients was 57.9 ± 10.0 years.
• > 20 percent of participants had at least one first-degree family member with a history of prostate cancer.
• Men with a baseline PSA level of 0.1 to 1.0 ng/ml were at greatly reduced risk for prostate cancer compared to men with a baseline PSA level of > 1.0 ng/ml.
• Among 1,610 men with a baseline PSA level of ≤ 1.0 ng/ml (55 percent of the total)
  • The 10-year rate of diagnosis with prostate cancer was 3.4 percent.
  • 90 percent of the cancers diagnosed were low risk.
• Among 489 men with a baseline PSA level of 1.0 to 1.5 ng/ml (16.7 percent of the total)
  • The 10-year rate of diagnosis with prostate cancer was ≥ 14.9 percent
• Among 297 men with a PSA level of 3 to 10 ng/ml (10.2 percent of the total)
  • The 10-year rate of diagnosis with prostate cancer was 39.0 percent

The authors conclude that

• Optimal PSA screening frequency for men with baseline PSA levels between 0.1 and 1.0 ng/ml may be as high as every 10 years.
• Their approach has the potential to
  • Reduce the cost of screening
  • Reduce the over-detection of inconsequential tumors
  • Maintain the detection of tumors for which treatment has been proven to reduce prostate cancer mortality.

It is also interesting that the very low risk for diagnosis of clinically significant prostate cancer within 10 years of follow-up among men with a PSA level of ≤ 1.0 ng/ml appears to correlate closely to the proposed baseline PSA cut-point of 0.7 ng/ml at age 45 (proposed some time ago by Vickers, Lilja, and others) that suggested a very low level of risk for diagnosis of clinically significant prostate cancer within the next 25 years.

Gelfond et al. are careful to point out that their data suggest a way forward in considering how to think about the value of PSA testing based on baseline PSA levels in well characterized groups of patients, but they do not offer a definitive solution to the problem. They acknowledge that the type of risk-adjusted PSA testing strategy which they propose — based on major reductions in the frequency of PSA testing (e.g., every 10 years in men with a PSA level of ≤ 1.0 ng/ml at baseline) — will lead to missing a very small percentage of clinically consequential prostate cancers. However, a strategy of this type would also save many thousands of men from unnecessary PSA testing, unnecessary biopsies, and the avoidable consequences of unnecessary over-treatment.

Filed under: Diagnosis, Risk | Tagged: baseline, Diagnosis, PSA, risk, testing |