Smoking raises cervical cancer risk

Cigarette smoking increases the risk of developing cancer of the cervix in women, with the number of cigarettes smoked every day and the age at which smoking began.Researchers from the Cancer Research UK in Oxford evaluated the data from 23 studies on the effects of smoking on cervical cancer risk, involving 23,017 women, who were initially free of cervical cancer. It was found that current smokers have a 60 percent greater risk of cervical cancer than women who never smoked. There was no association between smoking duration and risk of cervical cancer, but there was a correlation with the age at which smoking began.One possible explanation for the association is that the duration of smoking was reported less accurately than the age at which the smoking started, and age at the start of smoking is acting as a surrogate for duration of smoking, i.e. an earlier age at starting smoking is a marker of longer duration. Eight of the 23 studies included data on cervical infection with human papilloma virus (HPV), which has been linked to most cases of cervical cancer. In these studies, women who tested positive for HPV had a risk of cervical cancer almost two-fold higher than HPV-negative women. The findings confirm that smoking is a risk factor for cervical cancer, as the association was present also in women who were HPV-positive, strongly suggesting that the association is not just due to confounding between sexual behaviour and smoking.