What many don't realize is that lung cancer is the leading cancer killer of women, responsible for 27 percent of all cancer deaths, ahead of breast and colorectal cancer, according to the latest federal statistics. And women may be more susceptible to the disease than men, research suggests, a fact many women -- and their doctors -- may not realize.

"Lung cancer causes more deaths among women than breast, uterine and ovarian cancers combined, but I don't think this is on women's radar screens at all," said Dr. Jyoti Patel, an oncologist at Northwestern Memorial Hospital in Chicago, and a specialist in women's lung cancer.

"Women who smoked when they were young, stopped 30 years ago and did all the right things since are underestimating their risk for lung cancer," added Patel, who co-authored an April 2004 report in the Journal of the American Medical Association on the risks of lung cancer in women.

That lack of awareness is often compounded by ill-informed doctors, she said.

"When I was in medical school, we were taught that lung cancer is a disease for men 60 years and older who smoke, and most interns today still think that is typical," Patel said. The result: Many doctors don't talk to their female patients about the risks of lung cancer.

But the facts are quite different. More than one in four cancer deaths among women in 2003 were due to lung cancer. An estimated 70,000 women died from lung cancer in the United States, compared to approximately 39,000 women who died from breast cancer, according to the American Cancer Society.

There are myriad reasons for both the prevalence of lung cancer among women and the high death rate from the disease, health professionals said.

The main culprit, predictably, is smoking.

"If you ask me for the top 10 causes for lung cancer, I'd say nine of them are smoking," said Patel.

Nearly one out of five women smoke, and many more are former smokers, she noted.

"The risk of developing lung cancer remains for 20 years after quitting, and then the risk drops by half," said Viviana Simon, director of scientific affairs for the Society for Women's Health Research, in Washington, D.C.

But for women, there are other factors linked to the disease that are gender-based, she said.

Non-smoking women are more likely to get lung cancer than non-smoking men, Simon said. More women than men develop small-cell lung cancer, which is more aggressive than other lung cancers and harder to cure. There is some evidence that men's and women's hormonal differences could affect the course of the disease. And women, no matter what stage of lung cancer they have, live longer than men at the same stage of disease, she said.

Yet there's little research into why these gender differences exist and what they could mean for treatment of the disease.

"There has to be more awareness in the scientific community, the clinical community and the public about the dangers of lung cancer and the differences in prevalence and risk for women and men," Simon said.

Research into lung cancer is negligible compared to other cancers, Patel said, with only $1,300 spent on research per patient death from lung cancer. This compares to $30,000 per patient with HIV, $18,000 per breast cancer patient, and $10,000 per prostate cancer patient, she said.

This is partly because there are fewer survivors of lung cancer to lobby for a cure for the disease. But there's also a cultural bias against lung cancer patients who smoke -- that they brought the disease on themselves, Patel said, adding women tend to be particularly susceptible to this line of thought.

"Women who have smoked marginalize themselves," Patel said. This sense of guilt often leads them to be lax about their health care, and to think they're getting what they deserve.

"I say to my patients that they made one bad choice, but I don't think anyone would say that one bad choice means they deserve cancer," she said.

Both Patel and Simon said more research is needed if lung cancer deaths are to be reduced. Presently, there are few reliable screening techniques for early detection. And while there are some promising new drugs to treat the disease -- Iressa and Tarceva are two that are effective, especially for women -- more science needs to be applied to the task of a cure, Patel said.

In the meantime, Patel recommends that women become more proactive about their risk for lung cancer, even if they don't smoke or have never smoked.

"If women feel a lump in their breast, they go to the doctor quickly," she said, and the same sound approach should apply to lung cancer risk.

Patel recommends paying attention to a cough. Coughs can signal lots of problems, from post nasal drip to a cold. But a cough that "changes character" in any way, in frequency or severity, means you should see a doctor. Similarly if you have shortness of breath, are awakened at night by coughing or have blood in your sputum, you should see a doctor and tell him about your concerns, she said.