Modified Gleason Grade of Prostatic Adenocarcinomas Detected in the PLCO Cancer Screening Trial

Abstract

We determined the modified Gleason grade of prostatic adenocarcinomas detected in PLCO to assess grade distribution and compare modified Gleason grades of cancer detected in the intervention arm (organized annual screening) vs the control arm (opportunistic screening). Modified Gleason grading was performed in 859 radical prostatectomy cases by a single urological pathologist. We compared the proportion of cases with high grade disease in the screened arm vs the control arm by logistic regression analysis. In the intervention arm a modified Gleason score of 5, 6, 7 (3+4), 7 (4+3), 8, 9 and 10 was assigned in 3.6%, 43.3%, 39%, 7.4%, 3.5%, 3.2% and 0.1% of cases, respectively. In the control arm a modified Gleason score of 5, 6, 7 (3+4), 7 (4+3), 8, 9 and 10 was assigned in 3.0%, 35.7%, 46.4%, 7.1%, 5.4%, 1.9% and 0.5% of cases, respectively, after correcting for high grade disease over sampling. A high grade modified Gleason score of 7 or greater was detected in 53% of cases in the intervention arm vs 61.3% in the control arm after correction (p=0.019). The median modified Gleason score was 7 (3+4) in each arm. A significant percent of cancers in each arm had a component of high grade disease. The modified Gleason grade of prostate cancers detected by organized annual screening was slightly lower than the modified grade of those detected by opportunistic screening. This is an expected consequence of more intensive screening.