Prostate cancer and chip specimens: complete versus partial sampling.

During a nine-year period, 850 routine prostatectomy specimens were examined by placing all of the tissue in blocks for complete microscopic examination. Of these specimens, 711 were obtained from patients in whom cancer had not been diagnosed previously; 61 cancers were found in this group, with 49 of these cancers from glands that had not been considered questionable on clinical examination. Review of the material suggests that for optimal partial sampling of transurethral prostatectomy specimens, five blocks should be submitted; this method is economical and will detect approximately 90 per cent of cancers, including all those consisting predominantly of Gleason pattern 4 or 5, all progressive cancers, and all cancers identified clinically as stage 3 or 4. The detection of all focal cancers probably requires examination of all tissue, but such detection may be unimportant to the patient's prognosis.