Smoking does not put women at higher risk of lung cancer than men

Women who smoke are no more likely to develop lung cancer than men who smoke. Women who have never smoked, however, do seem to be at higher risk of developing the cancer than men who have never smoked. These are the conclusions of authors of a study in an Article published early Online and in the July edition of The Lancet Oncology.

Cigarette smoking is thought to cause up to 90% of lung cancers in the USA. But whether or not smoking makes women more susceptible to lung cancer has been often debated amongst scientists, and research so far has produced conflicting results.

To clarify the issue, Neal Freedman from the National Cancer Institute, Rockville, MD, USA, and colleagues, analysed data from nearly half a million American men and women on their smoking habits, correlating that with rates of lung cancer in the group.

The 279,214 men and 184,623 women who were included in the study were aged between 50 and 71 years, and came from eight US states. Among other questions about diet, alcohol and physical exercise, they were asked whether they currently smoked or had ever smoked (and if so, how many cigarettes per day).

The researchers found that, overall, 1.47% of men and 1.21% of women in the study developed lung cancer. Women who had never smoked were 1.3 times more likely than men who had never smoked to develop lung cancer. Smoking was strongly associated with cancer risk in both men and women. Current smokers of more than two packs per day were about 50 times more likely to develop lung cancer then never smokers. Women smokers were slightly less likely (0.9 times) than men who smoked comparable amounts to develop the disease.

When the team looked at the incidence of different types of lung cancer, they found that in people who had never smoked, adenocarcinomas were more common in women than men, but rates of small cell, squamous, and undifferentiated tumours were similar in both sexes. In smokers, incidence rates for squamous tumours were twice as high in men than women, but the rates for the other tumours were similar in both sexes.

The authors conclude: "Our findings suggest that women are not more susceptible than men to the carcinogenic effects of cigarette smoking in the lung. Vigorous efforts should continue to be directed at eliminating smoking in both sexes".

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