Quality assurance in the laboratory diagnosis of prostate cancer

AgNOR quantity in needle biopsy specimens of prostatic adenocarcinomas: correlation with proliferation state, Gleason score, clinical stage, and DNA content

Aims-To define the relation between the quantity of silver stained nucleolar organiser regions (AgNORs) and histological grade, clinical stage, DNA content, and MIB-1 immunostaining in needle biopsy specimens of prostatic adenocarcinomas.Methods-Histological grade was determined according to the Gleason system. AgNOR quantity, DNA content and MIB-1 immunostaining were evaluated by image cytometry on routine histological sections stained with silver, Feulgen reaction and MIB-1 antibody, respectively.Results-The mean AgNOR area increased with increasing Gleason score. A significant difference was found in the AgNOR values between low, intermediate and high grade tumours. Patients with clinically localised tumour (stages A and B) had lower AgNOR values than patients with advanced disease (stages C and D), but the difference in the mean AgNOR values between the two groups was not statistically significant. Non-diploid tumours had a significantly higher mean (SD) AgNOR area than diploid tumours (3.68 (1.04) mum(2)v 2.73 (0.60) mum(2), respectively), while no significant difference was observed in the mean AgNOR values between aneuploid and tetraploid tumours (3.68 (1.04) mum(2)v 3.70 (1.05) mum(2)). When AgNOR and MIB-1-PI values were compared using linear regression analysis, a highly significant correlation was found.Conclusions-These data demonstrate that AgNOR quantity reflects the proliferative potential of prostatic adenocarcinomas, and is significantly related to histological grade and DNA content. The ease of application on routine sections, maintaining the morphological integrity of the tissue, the ability to evaluate selected histological areas of limited size and objective quantification by image cytometry make the AgNOR method particularly suitable for cell kinetic analysis in prostatic needle biopsy specimens.

Incidental Prostatic Carcinoma

Incidental carcinoma of the prostate is defined as an incidentally detected cancer without any clinical manifestation, i.e. latent. Clinically, it is diagnosed mostly by TUR and is staged as T1a and T1b according to the TNM classification. There is clinical understaging, however, of up to 27% for T1a and 68% for T1b. Although the subdivision seems justifiable on the basis of the progression rates (8% and 63% respectively), it is not a useful indicator of the natural history of the incidental carcinoma. Pathological staging of TUR specimens is far from standardized, with regard to both the different sampling methods and the commonly-used classifications. Since the T1 staging system is based more on how the cancer is identified than on classifying its pathology, different methods should be used for a full clinical understanding of an incidental carcinoma. Distinguishing cancers as clinically important or not allows a better prognostic indication compared to the staging systems, which can still not be considered as precise indicators of whether to treat the cancer or wait and see. Unfortunately the true prognostic factors cannot be directly deduced from the currently used sampling methods of TUR specimens. A complete diagnostic assessment should be carried out after initial diagnosis of incidental prostatic cancer in order to appreciate its clinical importance. Basically both revision of the material by the pathologist and further clinical investigation are useful. Lastly, the need for close co-operation between urologists and pathologists should be stressed.