Summary The expression of 5T4, an oncotrophoblast cell surface antigen was examined in 72 colorectal and 27 gastric carcinomas, with immunoperoxidase technique, on frozen sections.Highly significant association was found between 5T4 expression in the malignant cells and metastatic spread. The results suggest that the appearance of 5T4 molecules in cancer cells reflects a change which may contribute to the development of metastatic potential.It has been shown that certain human tumour tissues and cell lines express membrane antigens otherwise found only on placental trophoblast and absent on normal tissues (e.g. Loke et al., 1980;McLaughlin et al., 1982). These proteins may exist to protect the semi-allogeneic foetus from immunological rejection and in a similar way allow tumour cells to evade host immunity. An improvement of understanding the role of these antigens in human cancer is likely to be the basis for achieving new approaches to both its identification and treatment. The 5T4 trophoblast cell surface antigen (Hole & Stern, 1988; shows a restricted pattern of expression in normal human tissues, but the antigen is present in a wide variety of transformed cell lines (Hole & Stern, 1988) and carcinomas (Southall et al., 1990;Jones et al., 1990). In these investigations of 5T4 antigen expression in limited numbers of different human carcinomas, no conclusions could be drawn as to possible correlations with established prognostic factors.The objective of the present study was to determine the relationship between 5T4 expression, tumour growth and stage of disease, in order to investigate the difference, if any, between 5T4 positive and negative carcinomas from the colon and stomach.
Materials and methodsSeventy-two colorectal and 27 gastric carcinomas were included in this study. Gastric specimens and 33 colorectal cancers were obtained at the Pomeranian Medical Academy, Szczecin, Poland, the other colorectal neoplasms were from various Departments of Surgery, Manchester. The histological type and stage of tumour (Table II) as well as the grading (Table III) were assessed from routine examination of paraffin-embedded sections, stained with haematoxylin and eosin. The stage of grouping was made according to the criteria of Dukes and to the criteria of the Japanese Research Society, for colorectal and gastric cancer respectively.
ResultsThe results of immunohistochemical evaluation are summarised in Table I. Overall the proportion of tumour specimens labelled with mAb 5T4 was 85% for colorectal and 81% for gastric carcinoma. However, there were two distinct patterns of immunohistochemical staining, either detection of positive labelling of the malignant cells and surrounding stroma (40% of colorectal and 56% of the gastric tumours) or strong positive reactivity of stromal elements alone (45% of colorectal and 26% of gastric tumours). When the tumour cells were labelled for 5T4 antigen, there was reactivity in all or nearly all malignant cells as evidenced by congruency with cytokeratin labelling. Only 11 colore...