Smokers who quit 15 years ago still at high lung cancer risk

People who kicked the butt as long as 15 years ago are still at high risk for lung cancer and should be screened, warn researchers.

The current lung cancer screening criteria set by the US Preventive Services Task Force (USPSTF) recommends CT screening for adults between ages 55 and 80 who have smoked at least one pack a day for 30 years and are still smoking or have quit within 15 years.

In a new study, lead author Ping Yang, epidemiologist at Mayo Clinic Cancer Centre, and colleagues found that two-thirds of patients with newly diagnosed lung cancer would not meet the current USPSTF screening criteria, suggesting a need to adjust the definition of patients at high risk.

They found that compared to other risk categories, patients who quit smoking for 15 to 30 years accounted for the greatest percentage of patients with lung cancer who didn't qualify for screening.

"We were surprised to find that the incidence of lung cancer was proportionally higher in this subgroup, compared to other subgroups of former cigarette smokers," Yang noted.

The common assumption is that after a person has quit for so many years, the lung cancer rate would be so low that it wouldn't be noticeable.

"We found that assumption to be wrong. This suggests we need to pay attention to people who quit smoking more than 15 years ago, because they are still at high risk for developing lung cancer," Yang added in a paper published in the Journal of Thoracic Oncology.

Equally important, the findings showed that expanding the criteria for CT screening would save more lives with an acceptable amount of radiation exposure and cost.

If true in large populations, the authors recommend that policymakers should consider changing the lung cancer screening guidelines to include people who quit smoking more than 15 years ago.