Lung cancer is a different disease in women than it is in men, researchers have said.

The female hormone oestrogen is partly to blame, according to a team at Northwestern University, Illinois.

Rates of lung cancer in women have increased significantly in recent decades while those for men have remained stable.

The research in the Journal of the American Medical Association also noted the effect of more women smoking.

Female smokers have a greater chance of developing lung cancer, and a higher risk of developing adenocarcinoma, which is the most common form of the disease.

But women also have better survival rates, the researchers said.

Numbers of women smoking continue to increase, while rates among men are falling.

Between 1990 and 2003 there was a 60% increase in lung cancer cases among women in the US. An estimated 68,500 American women will die from the disease this year.

The team at Northwestern University, and colleagues at Memorial Sloan-Kettering Cancer Center, New York, looked at previous research into lung cancer and found evidence that the differences in disease rates and survival could in part be due to oestrogen.

Studies have shown lung cancer cells have more oestrogen receptors on their surface than normal lung cells.

Therapy

Other research has indicated a link between oestrogen replacement therapy and adenocarcinoma and an interaction with smoking.

Dr Jyoti Patel, an oncologist at the university, said: “Lung cancer appears to be a different disease in women.

“Mounting evidence suggests that these differences could be due, in part, to oestrogen.

“Genetic, metabolic and hormonal factors all are important to the way women react to carcinogens and lung cancer.”

The researchers said women reacted better to some targeted therapies and they were now trying to work out why that was.

Professor Michael Seckl, professor of cancer medicine at Imperial College London, has researched the role of oestrogen and found a possible link in lung cancer patients.

He said the conclusion that the hormone was partly to blame for women’s different rates of disease and survival was a “plausible interpretation”.

Professor Seckl added: “It is hardly surprising - men and women are very different.

“The message needs to get out there that lung cancer is not just a male disease. Women do appear to be more at risk of lung cancer.”

Far more research into lung cancer was needed, he said, as it currently gets only 3% of cancer research money in the UK though it is the form of the disease that kills the most people.