New research suggests that young women who smoke more than a pack of cigarettes a day have a much higher risk of developing the most common type of breast cancer.

The study, published in the journal Cancer, shows that young women who smoke are 30 per cent more likely to develop oestrogen receptor positive breast cancer, compared with those who have never smoked.

More worryingly, those who are heavy smokers (a pack a day for at least a decade) were 60 per cent more likely to develop this form of breast cancer.

The majority of recent studies evaluating the relationship between smoking and breast cancer risk among young women have found that smoking is linked with an increased risk, but few have evaluated risks according to different subtypes of breast cancer.

The study, carried out by researchers at the Fred Hutchison Cancer Research Center in Seattle, Washington examined cases of breast cancer in nearly 1,000 women aged 20 to 44-years-old.

Lead researcher, Dr. Christopher Li and his team conducted a population-based study consisting of 778 patients with estrogen-receptor-positive breast cancer and 182 patients with triple-negative breast cancer. ER-positive breast cancer is the most common subtype of the disease, while triple-negative is less common but tends to be more aggressive.  The study also included 938 cancer-free controls.

The researchers found that young women who were current or recent smokers and had been smoking a pack a day for at least ten years had a 60 percent increased risk of ER-positive breast cancer. In contrast, smoking was not related to a woman’s risk of triple-negative breast cancer.

Dr Li says the study adds to the knowledge of a link between smoking and breast cancer.

“The health hazards associated with smoking are numerous and well known. This study adds to our knowledge in suggesting that with respect to breast cancer, smoking may increase the risk of the most common molecular subtype of breast cancer but not influence risk of one of the rarer, more aggressive subtypes,” Li said.

BCAC chair, Libby Burgess, says the study provides yet further ammunition for young women to quit smoking in order to protect their health.

“We already know that smoking is associated with greater rates of lung cancer and respiratory disease.  If you’re a woman, this study provides further evidence that smoking is seriously dangerous for your health.  It’s best not to start and if you are a smoker, you should take steps to quit as soon as you can.”

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