The death of Dana Reeve, widow of Superman actor Christopher Reeve, has drawn new attention to a disease the kills around 19,000 Canadians every year.

Reeve passed away Monday at the age of 44. She had been battling lung cancer despite never having smoked, nor having been exposed to second-hand smoke.

Her death --just seven months after she was diagnosed with the disease -- has brought new attention to a cancer that kills more Canadians every year than breast, colorectal and prostate cancer combined.

Lung cancer specialist Dr. Yee Ung told CTV's Canada AM the disease appears to be on the rise, especially among women.

"Firstly, we know the incidence of lung cancer in women is increasing primarily in relation to smoking, but about 10 to 15 per cent of lifelong non-smokers do get lung cancer," Dr. Ung said.

Statistics show that smoking causes more than 80 per cent of lung cancer cases, but one in five women who develop lung cancer have never smoked.

Comment: Is this what the statistics really show, or do they simply assume that if a smoker gets lung cancer, it is because of smoking?

Experts are still largely mystified as to why female non-smokers are developing lung cancer. Dr. Ung said it could be related to second-hand smoke or genetic factors that make women more susceptible.

And although lung cancer is one of the most preventable forms of cancer, it is also difficult to diagnose and treat. Patients generally don't develop symptoms of the disease until it is too late to do much about, Ung said.

"The key is that often times the lung cancer is diagnosed unfortunately late. And once lung cancer has spread outside of the lungs we unfortunately don't have a cure for it," Ung told AM.

The best course of action, he said, is to maintain regular checkups with a doctor and immediately report any symptoms that develop, such as shortness of breath or coughing up of blood.

New cancer treatments are offering hope to some cancer patients, Ung said, allowing physicians to better diagnose the disease and improve treatment with chemotherapy, radiation and "newer targeted therapies."

But despite progress, about 60 per cent of people with lung cancer still die within the first year of being diagnosed, statistics released by the American Cancer Society reveal.

Most lung cancers occur in older people, the society says, with just three per cent affecting people under the age of 45, regardless of smoking status.

Globally, lung cancer is the world's leading killer, with more than one million new cases each year, and an equal number of deaths.

In 2006 there were about 1.2 million new cases of lung cancer and about 1.3 million deaths worldwide, the ACS says.

About 49 per cent of patients are estimated to survive when the cancer is detected before spreading outside of the lungs.

Once it has spread to the chest, the survival rate drops to 16 per cent, and once it has spread to other organs the survival rate plummets to just two per cent.

Surgery is the preferred form of treatment, but chemotherapy and radiation are also often used.

Reeve's form of lung cancer was rare and difficult to diagnose, continued Ung.

Reeve, a singer-actress, was renowned for her unwavering support of her late actor-husband, who was paralyzed in a horse-riding accident in 1996 and died in 2004.

Reeve fought for better treatments and possible cures for paralysis through the Christopher Reeve Foundation, which she led after her husband's death.