Low PSA may not rule out prostate cancer
NEW YORK (Reuters Health) – Even if patients have
relatively low prostate specific antigen (PSA) levels, a
biological marker for the disease, abnormalities detected by
digital rectal examination (DRE) can help identify prostate
cancer, re-enforcing the importance of this procedure, new
study findings suggest.
Some doctors believe the use of DRE in patients with low
serum PSA levels – lower than 4 ng/mL – is not necessary.
To further investigate, Dr. Caleb B. Bozeman and colleagues
at Louisiana State University Health Sciences Center in
Shreveport identified 916 patients with abnormal DRE findings
and a PSA level lower than 4.0 ng/mL. Most patients underwent
standard rectal biopsies.
According to the team’s paper, published in the medical
journal Urology, prostate cancer was diagnosed in 81 men, or
The investigators found that the predictive value of the
DRE increased as PSA levels increased, with cancer detected in
1.8 percent of those with levels between 0.0 and 0.9 ng/mL,
versus 21 percent among those with levels between 3.0 and 3.9
Age was also a significant predictor, with cancer diagnosed
among 5.4 percent of those younger than 50 years and among 11.3
percent older than 70 years.
The authors also noted that during surgery, 19 percent of
the prostate cancers were diagnosed on the side opposite the
original abnormality, defined as “serendipitous detection.”
“Our study found that the abnormality on the DRE in
patients diagnosed with prostate cancer was most likely to
represent cancer and thus, in most patients, cancer was not
diagnosed serendipitously,” Bozeman and his associates write.
However, they add, “one could argue that patients with
abnormal DRE findings and a serum PSA less than 2.0 ng/mL could
simply be followed up closely and do not require a prostate
SOURCE: Urology, October 2005.