Peter Jennings died Sunday after a brief battle with lung cancer. He was 67.
ABC News anchors said they hope if anything positive can be taken from Jennings' death, it is a greater awareness of the dangers of smoking.
"I want to give a message," Barbara Walters said. "If you have kids who are smoking, for heaven's sake, tell them that we lost Peter."
Lung cancer is the worst cancer killer in America, taking more lives each year than breast, prostate and colorectal cancers combined, according to the American Cancer Society.
An estimated 160,440 Americans die each year from lung cancer, accounting for 28 percent of all cancer deaths. Over 173,000 new cases of lung cancer are diagnosed each year, accounting for 13 percent of new cancer cases, according to the ACS.
More than 87 percent of lung cancers are smoking related, according to the Lung Cancer Organization.
"I was a smoker until about 20 years ago," Jennings told the "World News Tonight" audience on April 5, 2005, when he announced he had been diagnosed with lung cancer. "And yes, I was weak and I smoked over 9/11."
Dr. Derek Raghavan, director of the Cleveland Clinic's Taussig Cancer Center, said that the instant a person stops smoking, he starts getting better. Three to five years after quitting, the risk of getting lung cancer is reduced by half. However, ex-smokers may feel worse before getting better.
"You destroy so many of the little hairs that … they take awhile to grow back," Raghavan said. "Before they can [feel any improvement], smokers sometimes report feeling a bit worse, so they say, 'I don't feel any better, why not smoke?' The fact is, nothing will make you healthier than not smoking."
Warning signs of lung cancer can also be confused with symptoms associated with long-term smoking. The three main warning signs are an increase of coughing that doesn't clear up, coughing up blood and sharp chest pains.
People with those symptoms should consult a doctor.
"Remember, it's not necessarily a death sentence," Raghavan said. "In my own practice I've seen people who, by the statistics would surely die, and yet they go on to live for years, even decades. It can happen."
Raghavan said there have been promising developments in the treatment of lung cancer, including innovative uses of radiation and surgery and drugs.
"But the fact is that stopping smoking is the most important thing we can do," Raghavan said. "There is no therapy that even comes close."