Cigarette smoking is responsible for at least 345,962 cancer deaths in the U.S. each year, according to a new study.
About 45% of those deaths are the result of cancers of the lung, bronchus and trachea, researchers reported Monday in the journal JAMA Internal Medicine. An additional 15% of the deaths are due to colorectal cancer, 11% are due to pancreatic cancers and 6% are due to liver cancers.
Scientists have determined that 12 types of cancer can be caused by smoking. When these 12 cancers are pooled together, nearly half of all deaths – 48.5% – can be blamed on cigarette smoking, the researchers calculated.
Lung cancer has the strongest link to smoking. The researchers estimate that 83% of lung cancer deaths in men and 76% of lung cancer deaths in women are the result of smoking.
Smoking also has an outsized role in cancers of the larynx. Fully 93% of larynx cancer deaths in women, along with 72% of larynx cancer deaths in men, are due to cigarette use, the researchers found.
The next tier includes esophageal cancer (with 51% of deaths tied to smoking), mouth and throat cancers (47% of deaths due to smoking) and bladder cancer (45% of deaths linked to smoking).
In another group are liver cancers, uterine and cervical cancers and stomach cancers, with 24%, 22% and 20% of deaths attributable to smoking, respectively.
Rounding out the list are kidney cancer (with 17% of deaths due to smoking), myeloid leukemia (15% of deaths traced to smoking), pancreatic cancer (12% of deaths linked to smoking) and colorectal cancer (10% of deaths tied to smoking).
To come up with these figures, the researchers – from the American Cancer Society, the National Cancer Institute, Harvard Medical School and the Fred Hutchinson Cancer Research Center – combined data from the 2011 National Health Interview Survey, the Cancer Prevention Study II and five studies that are known as the Pooled Contemporary Cohort. The people included in the analysis were at least 35 years old, and they were more educated and less racially diverse than Americans as a whole.
The new analysis does not include other forms of tobacco use, such as cigars and pipes, the study authors noted. Nor does it account for exposure to second-hand smoke, which is believed to be responsible for about 5% of lung cancer deaths.
But even with these limitations, the take-home message is clear, the researchers concluded.
"Continued progress in reducing cancer mortality, as well as deaths from many other serious diseases, will require more comprehensive tobacco control," they wrote.
"The silver lining," wrote Dr. Michael Ong, an internist and researcher at UCLA, "is that most smokers want to quit.