ABSTRACT
Cancer development is a long-term multistep process which allows interventional measure before the clincial disease emerges. the detection of natural substances which can block the process of carcinogenesis is a important as the identification of anti-tumoral drugs since they might be used in chemoprevention of cancer in high-risk groups. In vivo rodent models of chemical caecinogenesis have been used to study plant-derived inhibitors of carcinofenesis such as indols, coumarins, isothiocyanates, flavones, phenols and allyl-sulfides. Since the standard in vivo rodent bioassay is prolonged and expensive, shorter reliable protocols are needed. Two in vivo medium-term protocols for evaluation of modifiers of carcinogenesis are presented, one related to liver and the other to bladder cancer. Both protocols use rats, last 8 and 36 weeks and are based on the two-step concept of carcinogenesis: initiation and promotion. The protocols use respectively the development of altered foci of hepatocytes expressing immunochistochemically the placental form of gluthation S-transferase and the appearence of pre-neoplastic urothelium and papillomas as the "end-points". the use of these protocols for detection of plantpderived inhibitors of carcinogenesis appear warranted.
Subject(s)
Animals , Anticarcinogenic Agents/isolation & purification , Anticarcinogenic Agents/therapeutic use , Antibodies, Neoplasm , Plants, Medicinal/chemistry , Drug Screening Assays, AntitumorABSTRACT
A elevada taxa de recorrência do câncer de bexiga é parcialmente devida a processo neoplasico multifocal do urotélio, concomitante ou posterior ao diagnóstico da primeira lesäo tumoral. Esta observaçäo justifica o seguimento rigoroso dos pacientes após ressecçäo parcial destas neoplasias. Os autores relatam umc caso de carcinoma "in situ" näo-papilífero de bexiga, detectado pelo exame citológico da urina três anos após ressecçäo de carcinoma papilífero. Depois de discutir este encontro de lesäo urotelial pré-invasiva näo papilífera em paciente de alto rico e apontar a concomitância com hiperplasia nodular depróstata, os autores salientam a eficiência do escrutínio citológico na populaçäo de alto risco para neoplasia vesical