[Characteristics of prostatic cancer undetected in the first assessment of a screening program. Quality control]

To study the results of the second round in the subjects with negative tests in the first round of a prostate cancer screening program and to analyze the characteristics of the tumors that were not detected in the first round.

Of 5188 males evaluated in a prostate cancer screening program, 976 with negative tests in the first round (804 with PSA < or = 4 ng/ml; 172 with PSA > 4 ng/ml and a negative biopsy) accepted to undergo subsequent tests. During the second round, 163 biopsies were indicated. The biopsy results and the characteristics of the tumors detected were analyzed.

The biopsy yield was higher (but not significantly) in the first round (80 cancers/481 biopsies; 16.6%) than in the second round (13 cancers/115 biopsies; 11.3%). Of the 163 biopsies indicated in the second round, 115 were performed and 13 cancers were detected (10 of these patients had a high PSA in the first round). The univariate analysis showed no differences for age, PSA, PSA density, prostate volume, transrectal US findings, or Gleason score in the cases diagnosed in the first round and those detected in the second round. However, there was a higher proportion of tumors with abnormal DRE in the cancers detected in the first round than in the second round, (31.3% vs 7.7%, respectively; p = 0.02). There was a higher proportion of tumors clinically detected in the second round than in the first round (100% vs 75%, respectively; p = 0.043). The multivariate analysis only showed differences for the DRE findings (p = 0.045).

A significant number of tumors are undetected in prostate cancer screening programs. Although the biopsy yield may be slightly lower in subsequent rounds, there is a strong trend of detecting more localized tumors (and therefore potentially curable). We have found no correlation between a greater prostate volume and tumors that were undetected in the first round.