BACKGROUND: Gastric tumorigenesis is a complex mechanism where genetic, enviromental and infeccious interferences may occur. In the last few years, advances in molecular biology brought a new way in the research of the malignancies using tumoral markers and imunohistochemistry. AIM: To describe the cytophotometric expression of tumoral markers Ki-67 and caspase-3, analyzing optical density and labeling index as parameters in gastric adenocarcinoma. To compare the labeling index and optical density of Ki-67 and Caspase-3 in gastric adenocarcinoma. METHODS: Fifty eight paraffin blocks containing gastric adenocarcinomas specimens were collected in the Serviços de Anátomo-Patologia do Hospital do Gama - Brasília (DF) and Hospital Dom Orione - Araguaina (TO), being analyzed at CITOLAB - Cytology and Hystopathology Laboratory Ltda, in Curitiba (PR). A total of 31 of the blocks were used for hystological studies. Immunohistochemistry was performed utilizing the SAMBA 4000 computerized analysis system. RESULTS: Of the 31 slides studies, 15 (48%) were marked by Ki-67, 22 (71%) were marked by Caspase-3 and 14 (45%) were marked by both of the tumoral markers. CONCLUSIONS: Cytophotometric expression of Ki-67 was observed in 15 of the slides studied, presenting an average labeling index of 36,85%, where as the optical density showed an average of 29,33 pixels. Cytophotometric expression of Caspase-3 was observed in a total of 22 slides, presenting an average labeling index of 87,71% and optical density of 60,74 pixels. When comparing the labeling indexes of both of the tumoral markers Ki-67 and Caspase-3 concerning the 14 slides analyzed, a significant difference (P<0,001)
