Most people are aware that smoking rates are (and have been) on the decline. That’s a great thing from a public health standpoint. What’s not so great? That same decrease in smoking rates may be to blame for an increase in lung cancer mortality, according to a group of Mayo Clinic researchers.
It all has to do with screening. That is, smokers who quit earlier find themselves ineligible for low-dose CT scans, a vital tool in the identification and diagnosis of lung cancer.
“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.”
The study consisted of about 140,000 people, all from Olmstead County, MN aged 20 or over beginning in 1984. Followed through 2011, lung cancer cases were identified using the Rochester Epidemiology Project database and confirmed by pathology definition of the World Health Organization.
The standard criteria for CT scanning includes smoking adults aged 55 to 80 who have smoked for at least 30 pack-years (one pack per day for 30 years) and have not quit smoking. All told, 1,351 people were diagnosed with lung cancer during the study. The overall lung cancer rate dropped, but actually increased in women.
The most important factor in CT scanning is the proportion of adults who smoked at least 30 pack years, which declined over the course of the study. At the same time, the number of people who had quit for 15 years or more increased. And yet, some of these people developed lung cancer anyway – many of whom were unable to receive proper treatment due to CT scan ineligibility.
Dr. Yang says public policy needs to change to include smokers who have smoked less than 30 pack-years, as well as those who have quit for more than 15 years.
“We don’t want to penalize people who succeeded in smoking cessation,” she says.