Correlation between iododeoxyuridine and MIB-1 labelling index in gastric carcinoma and adjacent normal gastric tissue

Background: In vivo labelling with synthetic thymidine analogues, such as I ododeoxyuridine (IdU) and Bromodeoxyuridine (BrdU), has frequently been use d to estimate tumour proliferation. However, this method requires intraveno us administration of IdU or BrdU, thymidine analogues that are potential mu tagens. Recently, the monoclonal antibody MIB-1 has been developed, recogni zing the Ki-67 nuclear antigen, which is associated with cell cycle prolife ration and is found throughout the cell cycle (G(1), S, G(2) and M phases), but not in resting (G(0)) cells. We studied the correlation between the MI B-1 labelling index (LI) and the IdU labelling inner in normal and malignan t gastric tissue. Patients and methods: Twenty patients with gastric cancer received an intravenous injection of IdU (200 mg/m2) before surgery Specim ens were obtained fr om gastric carcinoma and adjacent normal gastric tissu e. The samples were fixed in formalin and immunohistochemical analyses of I dU LI and MIB-1 LI were performed The LI was defined as the percentage of l abelled nuclei of 5000 nuclei counted Results: The IdU LI ranged from 3.3% to 18.2% in gastric carcinoma and from 0.5% to 5.6% in adjacent normal gast ric mucosa, whereas the MIB-1 LT ranged from 4.2% to 46.0% in gastric cance l and from 1.3% to 25.1% in adjacent normal gastric mucosa. Comparison of I dU LI with MIB-1 LI, using the Spearman rank correlation coefficient test s howed a significant correlation between IdU LI and MIB-1 LI in normal gastr ic tissue (r=0.63, p<0.05). However; in gastric carcinoma no significant co n elation was found between either proliferation marker (r=0.07, N.S.). Con clusion: MIB-1 accurately reflects the in vivo IdU LI in normal gastric tis sue, whilst in gastric carcinoma the MIB-1 LI does not seem to be a substit ute for the in vivo IdU LI.