The monoclonal antibody (MAb) Ki-67, which is directed against a proliferation-associated nuclear antigen, was used to measure tumor proliferation in 165 carcinomas of the esophagus, stomach, colon and rectum with an indirect immunoperoxidase technique. The percentage of Ki-67-positive tumor cells (Ki-67 index) was evaluated with the point-counting method. The Ki-67 index in gastric cancers (mean, 24.8%; standard deviation, 11.1%) was significantly lower than in tumors of the esophagus (35.7 +/- 12.6%), colon (37.6 +/- 15.2%), and rectum (34.3 +/- 16.4%). A wide range of the Ki-67 index (5.9-75.3%) could be observed within the various tumor types. In recurrent colorectal carcinomas, the Ki-67 index significantly increased to 51.9%. The Ki-67 index was independent of pathologic (e.g., TNM-stage, grading, tumor volume, tumor site) and clinical variables (age and gender of the patients). A marked heterogeneity of Ki-67 expression within different tumor stages was noted. Statistically significant regional variations in tumor proliferation existed between different areas within the same tumor.

Summary The vascularisation of rectal and oesophageal carcinomas and of normal mucosa was studied using histochemical and immunohistochemical methods. Endothelial cells were stained for alkaline phosphatase (AP) using an azo-dye procedure. Histochemical results were compared with the immunohistochemical identification of endothelial cells using the monoclonal antibody BW200 recognising an epitope restricted to human endothelial cells. In Histochemical demonstration of alkaline phosphatase in the endothelium of the arterial part of the terminal vascular supply has been advocated for quantitative analysis of the vascularisation in human tumours (Mlynek et al., 1985). However, studies in a variety of different tumour types (Monis & Rutenburg, 1960) have shown that sometimes the simultaneous reactivity of stromal connective tissue may preclude the exact evaluation of blood vessels in human cancers.The capabilities of this histochemical method for the measurement of vascular density were therefore compared with an immunohistochemical technique using a monoclonal antibody directed against endothelium. This study was performed in rectal and oesophageal cancers because in these tumour types pre-and postoperative irradiation is often included in therapeutic regimens. Materials and methodsCryostat sections (5,um) of rectal (n=13) and oesophageal cancers (n= 17) and normal mucosa were air-dried, fixed in acetone and stained for alkaline phosphatase (AP) using an azo-dye method. Tissue sections were incubated in a solution containing diazotised triamino-tritolyl-methanechloride (New Fuchsine, CI no. 42520) and naphtol AS-BI phosphate as substrate (Stutte, 1967).For the immunohistochemical staining of vascular endothelium the monoclonal antibody BW 200 was used. This recognises an epitope on an antigen molecule restricted to human neoplastic and non-neoplastic endothelial cells (Alles & Bosslet, 1986 (Chalkley, 1943). In normal tissues, vascular parameters were evaluated in the mucosa and submucosa. It has been shown (Mlynek et al., 1985) that quantification of vascular parameters in normal colorectal mucosa was independent of the spatial orientation of vessels on histological sections. Therefore, only sections cut perpendicularly and not parallel to the luminal surface were used, allowing a simultaneous analysis of vessels in the mucosa and submucosa. Only this spatial orientation of histological sections rendered it possible to analyse the capillary plexus near the basal epithelial cells of normal oesophageal mucosa, which might have been missed on sections cut parallel to the luminal surface. In six patients, comparative microscopic analysis of two randomly oriented histological sections cut from a single tumour block did not reveal a preferential spatial orientation of vessels in tumours.Sections were examined through a graticule with a regular arrangement of 25 crosses inserted in a 10x eye-piece in combination with a 40 x objective. Sections were scanned by systematic sampling (Weibel, 1979 Because not all the vessel...