Welcoming Remarks.- An Overview of Current Research Efforts on the Application of Biological Markers to Carcinogen Testing.- In Vivo Tests.- Chairmans Overview on In Vivo Tests.- The Occurrence of Neoplasms in Long-Term In Vivo Studies.- Markers of Liver Neoplasia Real or Fictional?.- Early Morphologic Markers of Carcinogenicity in Rat Pancreas.- Rodent and Human Models for the Analysis of Intestinal Tumor Development.- Effect of Diet on Intestinal Tumor Production.- Tumor Antigens as Markers for Carcinogens.- In Vitro Tests.- Chairmens Overview on In Vitro Tests.- Biochemistry and Biology of 2-Acetyl-Aminofluorene in Primary Cultures of Adult Rat Hepatocytes.- Relating In Vitro Assays of Carcinogen-Induced Genotoxicity to Transformation of Diploid Human Fibroblasts.- Evaluation of Chronic Rodent Bioassays and Ames Assay Tests as Accurate Models for Predicting Human Carcinogens.- Indices for Identification of Genotoxic and Epigenetic Carcinogens in Cell Culture.- Enzymes.- Chairmens Overview on Enzyme Markers.- Aryl Hydrocarbon Hydroxylase Activity of Mice and Humans.- Gamma-Glutamyl Transpeptidase Expression in Neoplasia and Development.- Ornithine Decarboxylase: Alterations in Carcinogenesis.- Human Tumors: Enzyme Activities and Isozyme Profiles.- Enzyme and Isoenzyme Patterns as Potential Markers of Neoplasia in Breast Tissue.- Oncofetal Antigens and Hormones.- Chairmens Overview on Oncodevelopmental Markers.- Alphafetoprotein as a Marker for Early Events and Carcinoma Development During Chemical Hepatocarcinogenesis.- Human Chorionic Gonadotropin and its Subunits as Tumor Markers.- Prostaglandins and Cancer.- Monoclonal Antibodies.- Chairmens Overview on the Use of Immunoanalytical Method for the Characterization and Quantification of DNA Components Structurally Modified by Carcinogens and Mutagens.- Immunological Approaches for the Detection of DNA Modified by Environmental Agents.- Detection of Thymine Dimers in DNA with Monoclonal Antibodies.- Immunolc,