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During the 1950s, the evidence was clearly sufficient to establish the carcinogenicity of tobacco smoking (1). By the end of the 1950s, convincing evidence linking smoking with lung cancer and other cancers had been obtained from case–control and cohort studies, carcinogens had been identified in tobacco smoke, and cigarette smoke condensate had been shown to cause tumors when painted on the skin of mice. Since then, the numbers of deaths attributable to tobacco smoking have sharply increased, reflecting the heavy smoking patterns of previous decades. It has been estimated that tobacco smoking is currently responsible for approximately 30% of all cancer deaths in developed countries, and that if current smoking patterns persist, an epidemic of cancer attributable to tobacco smoking is expected to occur in developing countries (2). In addition, smoking causes even more deaths from vascular, respiratory …