Smoking may be important

EDITOR—The review by McPherson et al on the epidemiology of and risk factors for breast cancer states that: “Smoking is of no importance in the aetiology of breast cancer.”1 The authors seem to be unaware of the mounting evidence that supports the relation between tobacco smoke and breast cancer. Seven of the eight studies that examined the relation between passive smoking and breast cancer suggest that there is an association between an increased risk of breast cancer and passive long term exposure to smoke among women who have never smoked; this is particularly true in cases of breast cancer occurring before menopause.2^–4

Furthermore, when passive smoking was controlled for in these studies, active …