Operational epidemiology of cancer.

Operational epidemiology is an action-oriented epidemiology directly aimed at cancer control. This approach has been elucidated by illustrating examples pertaining to cancer of oesophagus, lung, and breast. Using data collected by retrospective and prospective studies on these types of cancer it was observed that relative risk increases substantially when the various contributory factors are taken into account. Thus, the relative risk of oesophageal cancer increases when combined with the intake of hot tea-gruel. Relative risk increases further when other factors, such as nutritional deficiencies and cigarette smoking are considered. These studies support the well-known hypothesis of initiator and promotor mechanism of carcinogenesis. A few other modifying factors are also illustrated. Based on these studies strategies for intervention are suggested.