A survey by Canadian researchers has discovered that childless women who smoke more than a pack a day (20 cigarettes) have as high a risk of breast cancer as do mothers who started smoking in their teens.

However, smoking mothers who have left their childbearing years behind them and managed to reach the menopause paradoxically have a lower risk of breast cancer.

Does every smoke cloud have a silver lining? (Lancet 2002; 360: 1044-9).