ABSTRACT
Pathogenesis is defined as ‘the manner of development of a disease’. An understanding of the causes of a given cancer is an integral part of formulating strategies for successful treatment, screening and prevention. We owe much of our current understanding to epidemiologists who have discovered associations between different cancers and a number of genetic and environmental factors. In many cases, these lead directly to malignancy, e.g. smoking and lung cancer. The causative factors can be divided into genetic, chemical, physical and viral. It is becoming increasingly clear that changes in the host genome are the final common pathway in the process of carcinogenesis whatever the initial aetiology. However, for most patients with cancer it is still not possible to identify why that particular person developed cancer. Some of the examples cited are for historical interest only.
