By Steven Reinberg
MONDAY, June 15, 2015 (HealthDay News) -- About half of U.S. deaths caused by certain cancers -- including lung, colon and pancreatic tumors -- can be attributed to smoking, a new American Cancer Society study estimates.
In 2011, nearly half of the almost 346,000 deaths from 12 cancers in people 35 and older were linked to smoking, the study found.
"Despite large declines in smoking in the United States over the last 50 years, smoking still accounts for the majority of lung cancer deaths," said study co-author Rebecca Siegel, the American Cancer Society's director of surveillance information.
The researchers looked at 12 cancers known to be caused by smoking. In 2011, they found that 346,000 people died from these types of cancer. The researchers also had data on current and former smoking, and found that almost 168,000 of these deaths were due to tobacco.
For some cancers, the researchers said smoking was responsible for more than half of the deaths. Almost 126,000 of the deaths attributed to smoking were from cancers of the lungs, bronchus and trachea. That is about 80 percent of deaths from those cancers linked to smoking, according to the study. Just under 3,000 deaths from cancer of the larynx were tied to smoking, which is about 77 percent of the deaths that occurred in 2012 from that type of cancer, the researchers said.
In addition, approximately half of the deaths from cancers of the oral cavity, esophagus and urinary bladder were due to tobacco use, the researchers noted.
Smoking was also cited as the cause of many deaths from cancer of the colon, kidney, liver, pancreas, stomach, cervix, and from myeloid leukemia, Siegel said.
The number of Americans who smoke has dropped from 23 percent in 2000 to 18 percent in 2012, the study said. Still, smoking-related cancer deaths will continue to increase over the next several decades, Siegel said, because it will take 30 to 40 years to see the consequences of smoking among current smokers.
The rates of lung cancer have been declining among men and have begun to decline among women. The lag in the decrease among women is because larger numbers of women took up smoking years later than men and were slower to quit, she explained.
"If we could reduce smoking, we would have a lot fewer cancers," Siegel said. Smoking cessation efforts are especially needed among the poor, she said. "The poor are twice as likely to be smokers as the non-poor," Siegel said.
"While we have made a lot of progress in tobacco control, there is still a lot to do," she said.
The report was published online June 15 as a letter in JAMA Internal Medicine.
Dr. Norman Edelman, a senior scientific advisor to the American Lung Association, said when people hear about smoking and cancer, they often think about lung cancer and nothing else.
"This study shows that there is a huge burden of other cancers caused by smoking in addition to lung cancer," he said.
Edelman said that smoking is a huge public health problem and remains the major cause of preventable deaths in the United States. "Things are better, but we are not out from under it by any means," he said.
Edelman urges smokers to quit. "Smoking is even more deadly than thought," he said. "It is the most deadly element in our environment that we can control -- at least in theory."