Digital rectal exam identifies prostate cancers with normal PSA

Even if patients have relatively low prostate specific antigen (PSA) levels, abnormalities detected by digital rectal examination (DRE) can help identify prostate cancer, new study findings suggest.

Some clinicians oppose the use of DRE in patients with low serum PSA levels < 4 ng/mL, in the belief that prostate cancers in these patients are likely to be coincidental findings. 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 < 4.0 ng/mL. Most patients underwent standard sextant transrectal ultrasound-guided biopsy. According to the team's paper in the October issue of Urology, prostate cancer was diagnosed in 81 (8.8%).The investigators observed that the positive predictive value of the DRE increased for greater serum PSA levels, with cancer detected in 1.8% of those with levels between 0.0 and 0.9 ng/mL, versus 21% among those with levels between 3.0 and 3.9 ng/mL (p < 0.0001).Age was also a significant predictor, with cancer diagnosed among 5.4% of those younger than 50 years and among 11.3% older than 70 (p = 0.03).Defining "serendipitous detection" as the presence of prostate cancer diagnosed on the side opposite a palpable abnormality following radial prostatectomy, the authors observed that 19% of cancers were diagnosed serendipitously. "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," Dr. Bozeman and his associates indicate.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 biopsy." (Source: Urology 2005;66:803-807: Reuters Health: Oncolink: November 2005.)