Cigarette smoking and site-specific cancer mortality: testing uncertain associations using extended follow-up of the original Whitehall study

Background: The relation between cigarette smoking and several malignancies is still unclear. We examined the association of cigarette smoking with death attributed to 15 cancer sites, 7 of which are regarded as having an uncertain relation with tobacco. Patients and methods: The original Whitehall study is a prospective cohort of 17 363 London-based male government employees (age 40-69 years) who were examined in the late 1960s and then followed up for a maximum of 38 years. Results: Following adjustment for demographic characteristics, risk factors, and prevalent disease, established positive cigarette smoking-cancer gradients were confirmed for carcinoma of the lung, stomach, pancreas, bladder, upper aero-digestive (including oesophagus), and liver, and for myeloid leukaemia. Among the cancers of uncertain relation with smoking, mortality rates for malignancy of the colon, rectum and prostate and for lymphatic leukaemia were elevated in current and/or former smokers. There was essentially no apparent relation between smoking and mortality from carcinoma of the brain or from lymphoma. Conclusion: In this study, cigarette smoking appears to be a risk factor for several malignancies of previously unclear association with tobacco use.