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 The U.S. Preventive Services Task Force (USPSTF) recommends that
doctors engage patients in shared decision making, with thorough
discussions about the risk and benefits of screening, before
patients get low-dose computed tomography (CT) scans (a form of
high-powered X-ray) to look for any abnormalities on their lungs,
researchers note in one of the studies in JAMA Internal Medicine.
The Centers for Medicare and Medicaid Services require proof of
shared decision-making before they will pay for the test, the
authors add.
To gauge whether this actually happening, the study team analyzed
recordings of 14 conversations between doctors and patients about
starting lung cancer screening. Every one of the physicians
recommended screening, and discussion of potential harms was almost
entirely absent from these talks.
"Conversations were uniformly brief and one-sided," said senior
study author Dr. Daniel Reuland of the Lineberger Comprehensive
Cancer Center at the University of North Carolina Chapel Hill.
While screening may reduce the chance of dying from lung cancer by
catching tumors sooner, most people don't benefit because hundreds
of patients need to be tested over many years just to prevent one
death, Reuland said by email. Most of the time, CT scans detect
nodules, or abnormal tissue, that aren't cancerous, he added.
"Unfortunately, figuring out which nodules are cancer is hard and
can require invasive procedures which can lead to complications and
out-of-pocket costs, even for the people without cancer," Reuland
said.
In addition to these "false positives," another of the potential
harms of screening that doctors are supposed to discuss with
patients is overdiagnosis – when screening catches a cancer that is
so slow-growing it might never have caused symptoms, or at least not
before the person died of some other cause.
"However, (these tumors) still usually get treated with chest
surgery or other treatments, because figuring out which tumors don't
need aggressive treatment is difficult," Reuland added.
On average, doctors in the study devoted only one minute to
discussing lung cancer screening, during conversations that lasted
an average of 13 minutes, the study found.
"For a cancer screening with such unclear net benefit and clear
harms, it is particularly important that patients understand this
balance before signing up for such a test," said Dr. Rita Redberg,
chief editor of JAMA Internal Medicine and author of an accompanying
editorial.
"This matters a lot to patients, as they would have no way of
knowing that their chance of benefit from the low dose CT is small
and their chance of harm is greater," Redberg, said by email.
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A separate study in the same journal examined the risk of
overdiagnosis after lung cancer screening. Researchers randomly
assigned 4,104 current or former smokers to receive annual
screenings or no screenings for five years, then followed patients
for an additional five years.
By the end of the follow-up period, 96 people assigned to screening
were diagnosed with lung cancer, and 64 of these cases were detected
by CT scans. In comparison, 53 people who didn't receive screening
were diagnosed with lung cancer.
Researchers estimated that about 67 percent of the cancers detected
by screening represented overdiagnosis. This group did start out
with a higher risk for lung cancer than the group that didn't
receive screening, the authors note.
"Overdiagnosis is a critical outcome to consider when making
decisions about participating in lung cancer screening or not," said
lead study author Dr. Bruno Heleno, who did the work at the
University of Copenhagen in Denmark and is now at the Nova Medical
School in Lisbon, Portugal.
"Unfortunately, research shows that it is difficult to be certain
about the true extent of overdiagnosis when screening with low-dose
CT-scans," Heleno said by email.
The USPSTF currently recommends that people aged 55 to 80 with a
history of smoking the equivalent of a pack a day for 30 years get
screened yearly with a low-dose CT scan (https://bit.ly/2geBJ7d).
Ex-smokers might want to think differently about screening than
current smokers, said Dr. Mark Ebell, a public health researcher at
the University of Georgia and coauthor of an editorial accompanying
the overdiagnosis study.
"I primarily encourage patients from 55 to 70 who are current
smokers, since they have the greatest benefit," Ebell said by email.
"Older patients in good health can also consider screening, although
it's uncommon to find a current smoker over 70 years that doesn't
have other serious medical problems that limit the benefit from
screening for lung cancer."
SOURCE: https://bit.ly/2w682O5 , https://bit.ly/2P3c0zr , https://bit.ly/2nADakV
and https://bit.ly/2nBYFl2 JAMA Internal Medicine, online August 13,
2018.
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