It has long been known that not only smoking but also passive smoking increases the risk of lung cancer and heart attack.
Now, researchers at the University of Tromsø have found that girls who were exposed to passive smoking in childhood have an increased risk of developing breast cancer several decades later, writes Forskning.no.
The Norwegian researchers make no secret of the fact that they have made groundbreaking discoveries, in studies which is published in the renowned medical journal International Journal of Epidemiology.
“As far as we know, our study is the first to estimate the proportion of breast cancer in never-smokers that can be attributed to exposure to passive smoking from parents in childhood,” the researchers write.
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1 out of 10
The study includes a total of 45,923 women who have never smoked themselves, born between 1929 and 1957. Two thirds of them had been exposed to passive smoking in childhood.
2185 of the women were diagnosed with breast cancer within 27 years.
1493 (243/100 000) of the women who got breast cancer were among those who had been exposed to passive smoking by the parents in childhood, while only 692 (217/100 000) breast cancer cases occurred among those who answered that they had not been exposed to this.
If you only look at the group that was exposed to their parents’ smoking in childhood, the researchers find that one in 10 cases of breast cancer can be attributed to this exposure.
For the entire study population of close to 46,000 women, the researchers find that one in 14 breast cancer cases can be linked to passive smoking in childhood.
This corresponds to seven percent of all breast cancer cases, and is a serious finding, considering that breast cancer is the most common form of cancer among women in Norway and the most common cancer of all worldwide.
According to figures from the Cancer Registry, 3424 women in Norway were diagnosed with breast cancer in 2020.
