– Lung cancer still the killer no.1 in USA, It’s typically discovered too late to be treated successfully, with about 85 percent of victims dead within five years of diagnosis, And nine out of 10 cases of the disease are tied to a single behavior — smoking.

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, a statistic that bears repeating in November, Lung Cancer Awareness Month.

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

“At this point, the progress in decreasing lung cancer death rates is due solely to men quitting smoking since the early 1990s,” says Dr. Michael Thun, vice president of epidemiology and surveillance research for the American Cancer Society.

The death rate for men fell from 90.6 deaths per 100,000 people in 1990 to 69.4 deaths per 100,000 in 2005, Thun says. But the death rate for women peaked in 1998 at 41 deaths per 100,000 and has remained in that range ever since, he says.

“Lung cancer rates have been falling in men since 1991 since men began to quit smoking,” Thun says. “They have leveled off in women but are not declining. Women started smoking later than men in our society and are having more trouble quitting.”