Earlier, retrospective studies based on Swedish and Danish databases have suggested that men in their 40s with a single PSA level of < 1.0 ng/ml are at low risk for a diagnosis of prostate cancer for up to 30 years after that initial, baseline PSA result.
Data presented by Weight et al. at the recent annual meeting of the American Urological Association in Atlanta (click here and see abstract no. 1219) now appear to confirm these earlier data — in a cohort of > 250 randomly selected American men followed with PSA tests since 1990.
The study by Weight et al. recruited 268 men, all aged between 40 and 49 years of age at the time of recruitment, beginning in 1990. These men all lived in Olmstead County, Minnesota, and all received biennial evaluation by a urologist, PSA screening, a transrectal ultrasound, and were asked to complete a questionnaire.
Seventy-five percent of these men had a baseline PSA of < 0.1 ng/ml at their first PSA test taken between the ages of 40 and 49 years.
Here are the results of this long-term study:
- The average (median) follow-up period was 16.3 years.
- For men with a baseline PSA < 1.0 ng/ml
- The 10-year estimate of low-risk vs. intermediate-risk prostate cancer was 0.5 percent.
- The 10-year estimate of low-risk vs. high-risk prostate cancer was 0.0 percent.
- The 15-year estimate of low-risk vs. intermediate-risk prostate cancer was 2.7 percent.
- The 15-year estimate of low-risk vs. high-risk prostate cacner was 0.0 percent.
- For men with a baseline PSA ≥ 1.0 ng/ml
- The 10-year estimate of risk for a diagnosis of prostate cancer was 9.5 percent
- The 15-year estimate of risk for a diagnosis of prostate cancer was 12.8 percent.
The authors conclude that, in this specific cohort of men,
- Not a single man with a baseline PSA < 1.0 ng/ml between the ages of 40-49 developed intermediate- or high-risk cancer with nearly 20 years of follow-up.
- Men with low PSAs were also very unlikely to develop a low-risk prostate cancer.
- 75 percent of men aged between 40 and 49 years of age could avoid annual PSA tests for the next 10 years if their baseline PSA is < 1.0 ng/ml.
This study appears to offer the first confirmatory evidence of the hypothesis originally proposed by Lilja and Vickers that a baseline PSA can accurately project long-term risk for clinically significant prostate cancer. It also appears to provide clear evidence that a baseline PSA level of ≥ 1.0 ng/ml in men in their 40s is an indicator of elevated risk for clinically significant prostate cancer, thus defining a subgroup of men who probably should receive regular PSA tests to monitor their risk over time (even if that risk is low, and immediate treatment is not necessarily recommended).