Differences in AgNOR quantity between colorectal cancer and corresponding metastases: are they useful for prognostic purposes?

In order to evaluate the relationship between primary colorectal adenocarcinomas and their metastases with regard to AgNOR proteins expression, we have performed a morphometric analysis of AgNOR silver precipitates (AgNORs) in advanced colorectal carcinomas (stage III-IV) as well as in corresponding lymph node and distant metastases. Surgical specimens studied consisted of 64 primary tumours, 56 lymph node and 43 hepatic or omental metastases; for each formalin-fixed paraffin-embedded specimen, silver staining according Ploton et al. (1986) was performed and the AgNOR area (NORA) relative to primary site, lymph node and/or distant metastases was calculated. A significant difference (P < 0.001) among the non-neoplastic colonic control mucosae and primary or metastatic neoplastic lesions was found, but no statistically significant differences were encountered among the categories of primary colorectal carcinomas and their lymph node or distant metastases. Moreover, on the basis of NORA data case per case, three groups of patients were selected. In particular, in the group 1 NORA values of metastases were higher than those of the corresponding primary carcinomas, while in the group 2, NORA values of metastases were lower than those of the corresponding primary neoplasms; no differences of NORA values were encountered in group 3. The cumulative patient survival estimated by the Kaplan-Meier method showed a worse prognosis for patients belonging to group 1, where higher AgNOR values, not only in primary carcinomas but also in lymph node and distant metastases, were found.