Article révisé par les pairs
Résumé : The current study deals with the setting up of a new tool that enables the benign versus the malignant nature of colorectal adenomas to be determined accurately. The 2 objectives are to determine (1) whether adenomas should, or should not, be included in a 2- or a 3-tier grading system, and (2) whether severe dysplasias and carcinomas in situ share common or different biological characteristics. The levels of expression of different types of glycoconjugates were characterized in a series of 166 colorectal specimens, including 14 normal, 90 dysplastic, and 62 cancerous cases. The glycoconjugate expressions were demonstrated for 5 lectins, namely, Arachis hypogaea (PNA), Dolichos biflorus (DBA), Amaranthus caudatus (ACA), Maackia amurensis (MAA) and Sambucus nigra (SNA). The glycoconjugates demonstrated by these 5 lectins belong to the family of the Thomsen-Friedenreich antigens. The binding patterns of the 5 lectins were quantitatively determined by means of computer-assisted microscopy. The quantitative data were submitted to discriminant analyses. Our results show that the specific glycochemical staining patterns could be identified unambiguously and without misclassification between benign (normal and low dysplasia) and malignant (ie, either as moderate/severe dysplasia, carcinoma in situ, or cancer) cases. The data also strongly suggested that (1) dysplasias seem to be distinguishable in 2 instead of 3 groups, that is, low versus moderate/severe (high); and (2) moderate/severe dysplasias are biologically distinct from carcinomas in situ. The methodology developed can be applied directly in routine diagnosis to identify moderate/severe dysplasia specimens already exhibiting features common to carcinomas, and which therefore should be treated consistently in view of the fact that our data strongly suggest that most moderate/severe dysplasias are still benign, whereas carcinomas in situ are real carcinomatous lesions.

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