Cancer will become world’s number one killer by 2010, as the number of people in poorer countries dying from the disease is expected to grow due to smoking, high-fat diets and other factors, the World Health Organization warned at the beginning of this month.

From all cancers, lung cancer appears to be a major reason of concern in the next years, as the number of people smoking is on the rise. It’s true that more people are trying to quit the habit but only few succeed.

About 1.3 billion people smoke globally. Smoking is the major avoidable cause of death and disease worldwide. Smoking is the main cause of lung cancer, but the unhealthy habit also increases the risk of many other cancers in women, including breast, oral, pharynx, larynx, esophageal, pancreatic, kidney, bladder, uterine and cervical cancers.

Tobacco killed 100 million people worldwide last century and will kill a billion in the 21st century, unless people understand that they actually kill themselves by smoking day by day and it’s usually too late when they realize it. Also, every country in the world should take measures in order to reduce smoking. Studies have showed that countries taking such measures have fewer smokers and the overall health is better than in other countries where no such measures were taken.

Lung cancer killed 160,390 people in 2007, according to the Lung Cancer Alliance. That's an average of 439 people a day. And tobacco caused 90 percent of those deaths, according to the U.S. National Cancer Institute.

“Smoking is the most lethal legal activity in our society,” said Dr. James Mulshine, a professor of internal medicine and associate provost for research at Rush University Medical Center in Chicago.

Unfortunately, lung cancer is discovered too late to be treated successfully, with about 85 percent of victims dead within five years of diagnosis.

What can we do to prevent lung cancer? Well, I guess quitting smoking or avoiding smoke from other smokers is one thing that could guard us from developing the disease. Then having a healthy diet and exercising regularly may be great ways to prevent any disease.