Q. If you had to give a league table for habits that promote cancer, how would you rate them in order of high to low risk?

A. Put smoking way at the top. Twenty cigarettes a day raise your risk of cancer by between 20 and 40 times normal. Alcohol is a fairly close second – moderately heavy drinking more than doubles your risk of stomach and liver, and the more you drink the higher the multiple becomes. Obesity does raise your risk of cancer, but the rise is quite a lot less than for the first two. A long way behind comes eating fatty foods. If you want to lower your risk of cancer, follow the healthy living code of exercise, healthy eating, no tobacco and only a little alcohol. However, there’s no guarantee.