Smoking elevates risk of breast cancer in postmenopausal women--study

In addition, researchers found strong evidence that passive smoking heightened the threat of breast cancer in women who had never smoked but were exposed to excessive environmental tobacco smoke as kids or as adults.

Link between smoking and breast cancer explored
In order to explore the link between smoking, passive smoking, and breast cancer, Dr Juhua Luo from West Virginia University and Dr Karen Margolis from the HealthPartners Research Foundation in Minneapolis carried out a large scale study.

For the purpose of the study, they analyzed the data of around 80,000 women, aged between 50 and 79 years from 40 health facilities across the United States.

A follow-up at 10 years revealed that 3,250 of those women went on to develop invasive breast cancer, the most common cancer affecting women worldwide.

The study subjects were asked questions pertaining to their smoking status, whether they were former or current smokers or had never smoked.

The current smokers were asked at what age they had picked up the habit and how often they lit up in a day. The former smokers were asked when they had quit.

In addition, information relating to passive smoking, such exposure to second hand smoke either at home, at work or in social settings, both as kids and adults was collected.

Findings of the study
Overall findings revealed that active smokers elevate their risk of developing breast cancer by nearly 16 percent after the menopause.

The danger of the malignancy was nine percent for former smokers.

The risk of breast cancer was the highest in women who had been smoking for over 50 years as opposed to those who had never lit a cigarette.

In addition, the danger of the malignancy was particularly high for women who had adopted the habit in their teenage.

The risk persisted for up to 20 years after they stopped smoking.

Exposure to passive smoking
The study found that exposure ranging from moderate to high levels of second hand smoke for a combination of years influenced the risk for developing breast cancer.

Non-smoking women who had been exposed to extensive passive smoking for over a decade in childhood, more than 20 years' in adulthood at home and over 10 years' in the work environment heightened their risk of the breast cancer by 32 percent.

"Our findings highlight the need for interventions to prevent initiation of smoking, especially at an early age, and to encourage smoking cessation at all ages", Dr Margolis concludes.

The findings of the research published online in today's issue of 'British Medical Journal.'