DNA image cytometry on biopsies can help the detection of localized Gleason 3+3 prostate cancers.

PURPOSE

In spite of classifications based on digital rectal examination, prostate specific antigen (PSA), transrectal echography and histological analysis, 20% to 40% of operated prostate adenocarcinomas are not yet organ confined. New diagnostic features to predict extracapsular invasion before treatment are needed to avoid surgical extraction within positive margins.

MATERIALS AND METHODS

A retrospective study was performed for 74 prostate adenocarcinomas with Gleason 3+3. A total of 54 organ confined tumors (T1T2) at digital rectal examination were compared with 20 nonorgan confined tumors (T3T4). Image cytometric DNA analysis was performed on prostate initial biopsies. DNA ploidy results were compared in both groups for values of PSA greater than 15, less than 15 and less than 10 ng/ml.

RESULTS

For a PSA rate less than 15 ng/ml, 83.8% of T1T2 were diploid vs 33% T3T4 (p = 0.042). For a PSA rate less than 10 ng/ml, 96% of T1T2 were diploid vs 33% T3T4 (p = 0.025).

CONCLUSIONS

DNA ploidy appears to be an interesting feature at diagnosis. When in doubt about the localized character of a tumor, DNA ploidy it makes it possible to predict a nonorgan confined tumor. Gleason 3+3 prostate cancers that are organ confined at digital rectal examination are more often diploid than T3T4 tumors. The prognostic interest in DNA ploidy is more reserved because of its correlation with PSA level.