Decline in smoking rates may increase lung cancer mortality

A decline in smoking rates may mean that many people who could have benefited from early detection of lung cancer are dying because they don't qualify for low-dose CT scans, according to a group of Mayo Clinic researchers. Their research appears in the Feb. 24 issue of JAMA, the journal of the American Medical Association.

"As smokers quit earlier and stay off cigarettes longer, fewer are eligible for CT screening, which has been proven effective in saving lives," says Ping Yang, M.D., Ph.D., an epidemiologist at Mayo Clinic Cancer Center. "Patients who do eventually develop lung cancer are diagnosed at a later stage when treatment can no longer result in a cure."

Dr. Yang says researchers and policymakers need to re-examine screening criteria to identify a greater proportion of patients who develop lung cancer.

"The existing screening program will become less effective at reducing lung cancer mortality in the general population, if they continue to use the same criteria," Dr. Yang says.

The study retrospectively tracked residents of Olmsted County in Minnesota who were older than 20 years from 1984 through 2011 - about 140,000 people. Lung cancer cases were identified using the Rochester Epidemiology Project database and confirmed by pathology definition of the World Health Organization.

Researchers determined the proportion of lung cancer patients who would have met CT scan screening criteria set by the U.S. Preventive Services Task Force. Those criteria, used by doctors and insurance companies, recommend CT screening for asymptomatic adults age 55 to 80 who have smoked at least 30 pack-years (one pack a day for 30 years), and are still smoking or have reduced consumption in the last 15 years.

A total of 1,351 people in the study developed primary lung cancer between 1984 and 2011. Researchers found that the incidence of primary lung cancer fell overall during the study period - but only for men by about one-third. Among women, the incidence of lung cancer rose 8 percent.

The cigarette smoking rate among adults in the U.S. dropped from 20.9 percent in 2005 to 17.8 percent in 2013, according to new data published by the Centers for Disease Control and Prevention in today's Morbidity and Mortality Weekly Report (MMWR).

That is the lowest prevalence of adult smoking since the CDC's National Health Interview Survey (NHIS) began keeping such records in 1965. The report also shows the number of cigarette smokers dropped from 45.1 million in 2005 to 42.1 million in 2013, despite the increasing population in the U.S.

"There is encouraging news in this study, but we still have much more work to do to help people quit," said Tim McAfee, M.D., M.P.H., director of the CDC’s Office on Smoking and Health. "We can bring down cigarette smoking rates much further, much faster, if strategies proven to work are put in place like funding tobacco control programs at the CDC-recommended levels, increasing prices of tobacco products, implementing and enforcing comprehensive smoke-free laws, and sustaining hard-hitting media campaigns."