ARGYROPHILIC NUCLEOLAR ORGANIZER REGIONS AND BROMODEOXYURIDINE AND (3)[H]-THYMIDINE LABELING INDEXES IN COLORECTAL-CANCER

The count of argyrophilic nucleolar organizer regions (AgNORs) has bee n proposed as a useful method for evaluating cell replication in human tumours. The current study was undertaken to compare AgNOR values in colorectal cancers with two better established methods for investigati ng cell proliferation such as bromodeoxyuridine (BrdUrd) and (3)[H]-th ymidine ((3)[H]dT) labelling indices (LIs). Because some concern still exists regarding accuracy and reproducibility of AgNOR quantifying me thods, we carried out a control study by independently repeating the s ame measurements (number, area and area per silver-stained NOR particl e) in two centres with different operators and computer-assisted image analysers on 40 colorectal carcinomas. AgNOR values recorded in the t wo centres were strictly correlated (r = 0.75; P < 0.001 for number; r = 0.62, P < 0.01 for area; r = 0.63, P < 0.001 for area per silver-st ained NOR particle) and the range of values were almost identical, The n, AgNOR values were compared with BrdUrd and (3)[H]dT LIs, respective ly obtained by in vivo incorporation and in vitro incubation in the sa me series of colorectal carcinomas. No correlation was found between A gNOR values and BrdUrd or (3)[H]dT LIs. BrdUrd and (3)[H]dT LIs were i nstead reciprocally significantly correlated, No evident correlation w as seen between LIs or AgNOR values and clinico-pathological parameter s of the tumour. In conclusion, in colorectal neoplasms, AgNOR values did not appear to relate with more direct parameters of cell prolifera tion. It follows that AgNOR reliability as a biomarker of cell prolife ration remains questionable.