Health risk: The earlier a woman starts smoking, the greater her risk, and it remains high for 20 years after she has given up. Women who have smoked are at greater risk of developing breast cancer in later life – even if they gave up the habit decades earlier. According to a study, women are 16 per cent more likely to suffer from the disease after the menopause – when most cases are diagnosed – if they smoke. The earlier a woman starts smoking, the greater her risk, and it remains high for 20 years after she has given up.

Overall, if she has smoked she is 9 per cent more likely to develop the disease, according to the U.S. research. The study also suggests that decades of passive smoking increases the risk of breast cancer by 32 per cent, particularly if the exposure occurred during childhood. Around 46,000 cases of breast cancer are diagnosed in the UK each year, and one in eight British women will develop the disease during their lifetime.

The highest breast cancer risk was found among women who had smoked for 50 years or more. Those who started smoking as teenagers were also at high risk. And the study suggests a 32 per cent raised risk among non-smoking women exposed to extensive passive smoking. Dr Margolis said: ‘Our findings highlight the need for interventions to prevent initiation of smoking, especially at an early age.’ Dr Rachel Greig, Senior Policy Officer at Breakthrough Breast Cancer, said: ‘The study suggests the earlier you start smoking and the longer you continue to do so, the higher your chance of developing breast cancer. We encourage all women not to smoke.’