Histological evaluation of prostatic cancer. 1. Reproducibility of tumour type.

It has been claimed that the histological type of prostatic carcinoma bears influence on the prognosis of the patient, and that different treatments have to be considered for different types of tumours. The primary aim of this study was to evaluate the reproducibility of the histological criteria for the ordinary acinic adenocarcinoma and ductal adenocarcinoma. From 85 prospective and consecutive cases of prostatic carcinoma all histological slides were examined on two independent occasions by each of 4 pathologists. The overall inter observer agreement and mean intra observer agreement were 0.69 and 0.74, respectively. The kappa coefficients of these inter and mean intra observer agreements were 0.39 (S.E. = 0.02) and 0.48 (S.E. = 0.08), respectively. Considering a dichotomous classification of pure acinic versus all other types of prostatic carcinoma, an overall inter observer agreement of 0.78 and mean intra observer agreement of 0.84 were found. The kappa coefficients of this dichotomous classification were 0.51 (S.E. = 0.03, inter) and 0.61 (S.E. = 0.11, intra), respectively. It is concluded that the criteria for differentiation between different histological types of prostatic carcinoma need to be improved.