Cancer can be attributed to many factors including population ageing and exposure to risk factors, such as smoking, unhealthy diet and physical inactivity and environmental pollution.

Cancer is already a serious health problem and will become increasingly so not only in terms of rank order, as infections are better controlled, but also in terms of incidence and mortality, which will both increase as populations continue to grow and age, and as risk factors for cancer associated with greater affluence, such as smoking and changes in diet (qualitative and quantitative), continue to increase.