Opening Remarks.- General Problems.- The World Health Organization's Programme for the Histopathological Definition and Classification of Tumours.- Investigation on the Epidemiological Significance of Detailed Cancer Data-Preliminary Results.- Respiratory Tract.- Multiplicity of Lung Tumour Classifications.- The Significance of Asbestos in Tissue.- Thyroid Gland.- Histologic Classification as a Problem in the Epidemiology of Thyroid Cancer.- Leukemia and Thyroid Carcinoma Found among A-Bomb Survivors in Hiroshima.- Alimentary Tract.- Migrant Studies in Alimentary Tract Cancer.- Histological Types of Gastric Cancer and its Relationship with Intestinal Metaplasia.- Liver.- Primary Carcinomas of the Liver in Hong Kong. Some Possible Aetiological Factors.- Recent Techniques and Hypotheses in the Epidemiology of Liver Cancer.- The Aflatoxins and Human Liver Cancer.- Prostate.- Latent Carcinoma of the Prostate.- Mortality and Morbidity of Prostatic Carcinoma.- The Incidence of Carcinoma of Prostate: An Epidemiological Survey.- Other Genital Organs.- Correlates of Histologic Differentiation of Carcinoma of the Penis Results from a Five Year Survey in Uganda, 1964-1968.- Cervical Carcinogenesis: An Epidemiologic Model Adaptable to Control Pro gram.- Breast.- Hormones in the Aetiology and Clinical Course of Breast Cancer.- The Ovarian Etiology of Human Breast Cancer.- Lymphomas.- Primary Intestinal Lymphoma: Clinical Manifestations and Possible Effect of Environmental Factors.- Detection and Assessment of Case Clustering in Burkitt's Lymphoma and Hodgkin's Disease.- Epidemiologic and Immunologic Considerations on the Pathogenesis of Burkitt's Tumor.- Etiology of Burkitt's Lymphoma.- Epidemics of Hodgkin's Disease.- Hodgkin's Disease in Childhood-AnEpidemiological Study in Northern Ger many.