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Wednesday, January 27, 2016
Heavy Smokers Who Quit More Than 15 Years Ago Still at High Risk for Lung Cancer and Should Be Screened Mayo Clinic Study Finds
January 27, 2016— Expanding lung cancer screening to include people who quit
smoking more than 15 years ago could detect more cases and further reduce
associated mortality, according to a study by Mayo Clinic researchers published
in the Journal of Thoracic Oncology.
decline in smoking rates has been, and continues to be, a critical step to
reduce lung cancer risk and deaths,” says the study’s lead author Ping Yang,
M.D., Ph.D., an epidemiologist at Mayo Clinic Cancer Center.
it also means that fewer people have benefited from early detection of lung
cancer, because more patients don’t qualify for low-dose CT scans.”
current lung cancer screening criteria set by the U.S. Preventive Services Task
Force (USPSTF) recommends CT screening for adults between the ages of 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.
a study published in JAMA in 2015, Dr. Yang and her colleagues found that
two-thirds of patients in the U.S. 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.
the current study, Dr. Yang and her colleagues set out to identify which
specific populations of individuals are at risk, but are being missed by the
current lung cancer screening criteria.
retrospectively tracked two groups of people with lung cancer: a hospital
cohort made up of 5,988 individuals referred to Mayo Clinic and a community
cohort consisting of 850 residents of Olmsted County, Minnesota.
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.
newly defined high-risk group constituted 12 percent of the hospital cohort and
17 percent of the community cohort.
were surprised to find that the incidence of lung cancer was proportionally
higher in this subgroup, compared to other subgroups of former cigarette
smokers,” says Dr. Yang.
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.
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.”
important, the current study found that expanding the criteria for CT screening
would not significantly add to the number of false-positive cases and would
save more lives with an acceptable amount of radiation exposure and cost.
Yang and her colleagues showed that expanding the criteria to include this risk
category could add 19 percent more CT examinations for detecting 16 percent
calculated the expansion would result in minimal increases in false-positive
results (0.6 percent), over diagnosis (0.1 percent), and radiation-related lung
cancer deaths (4 percent).
cancer rates are dropping, because smoking is decreasing, but that doesn’t mean
that our current screening parameters are good enough,” Dr. Yang says.
is understandable, because the relative importance of risk factors changes over
time. We need to adjust screening criteria periodically, so we can catch more
lung cancers in a timely fashion.
on our data, which are more recent and come from a well-defined population, I
think that we should take action to screen this group, which is at high risk of
developing the disease.”
recommends additional research to confirm if similar trends are being seen in
populations beyond Olmsted County Minnesota.
confirmed, she recommends that policymakers consider changing the lung cancer
screening guidelines to include people who quit smoking more than 15 years ago.
She also recommends that policymakers continue to re-examine lung cancer
screening criteria to account for changes in groups that are most at risk.