ASCO: Low-dose CT delivers more false positives in lung cancer screening
Patients who undergo lung cancer screening with low-dose CT (LDCT) are at high risk for receiving false-positive results, according to a National Institutes of Health (NIH) study presented Saturday at the 2009 American Society of Clinical Oncology (ASCO) meeting in Orlando, Fla.
Several studies evaluating whether lung cancer screening reduces cancer deaths have reported a high incidence of noncalcified nodules among those screened. However, Jennifer M. Croswell, MD, from NIH in Bethesda, Md., and colleagues said their study marks the first time that the cumulative risk of a false-positive result has been quantified.
The study included 1,610 patients who underwent LDCT screenings and 1,580 who underwent chest x-ray, according to the researchers. Participants were between 55 and 74 years old and current or former smokers. They underwent a baseline screening exam, a follow-up exam at one year and were followed for an additional year.
The authors said that false-positive results were defined as noncalcified nodules greater than or equal to 4 mm or other findings that indicated a suspicion of cancer that were later found to be noncancerous.
For a patient choosing to undergo LDCT, the researchers reported that the risk of obtaining a false-positive result is 21 percent after one scan and 33 percent after a second. Patients choosing to undergo chest x-ray screening have a false-positive risk of 9 percent after one test and 15 percent after two.
Of the patients who had false positives, Croswell and colleagues said that slightly more than half underwent follow-up imaging exams. In the LDCT group, 6.6 percent of patients with false positives underwent invasive diagnostic procedures and 1.6 percent had major surgery. In the x-ray group, 4.2 percent of patients with false positives underwent invasive follow-up procedures and 1.9 percent of the total patients in this group had major surgery.
Complication rates for patients who had invasive procedures were low, but a few patients had to be hospitalized for a collapsed lung or blood in the lung (less than 1 percent), and another 1 percent had to be given antibiotics for infections, the authors wrote.
They also reported that 6.6 percent of participants with a false-positive LDCT underwent an invasive diagnostic follow-up procedure, 1.6 percent had major surgery; and 4.2 percent of participants with a false-positive chest x-ray underwent an invasive diagnostic follow-up procedure, 1.9 percent had major surgery.
"All medical interventions--including screenings--have not only the potential to benefit patients but also the potential for harm," said Croswell, acting director of the NIH Office of Medical Applications of Research. "We want to give people who are considering lung cancer screening the information they need to make informed decisions about the tests they choose. False-positive results may create increased psychological stress in patients and an increased burden on the healthcare system."
Findings from the study indicated that patients who were current smokers or older than 64 years of age might have an increased risk of false positives, but because the sample sizes were small, the researchers concluded that more studies are needed to confirm the findings.
Several studies evaluating whether lung cancer screening reduces cancer deaths have reported a high incidence of noncalcified nodules among those screened. However, Jennifer M. Croswell, MD, from NIH in Bethesda, Md., and colleagues said their study marks the first time that the cumulative risk of a false-positive result has been quantified.
The study included 1,610 patients who underwent LDCT screenings and 1,580 who underwent chest x-ray, according to the researchers. Participants were between 55 and 74 years old and current or former smokers. They underwent a baseline screening exam, a follow-up exam at one year and were followed for an additional year.
The authors said that false-positive results were defined as noncalcified nodules greater than or equal to 4 mm or other findings that indicated a suspicion of cancer that were later found to be noncancerous.
For a patient choosing to undergo LDCT, the researchers reported that the risk of obtaining a false-positive result is 21 percent after one scan and 33 percent after a second. Patients choosing to undergo chest x-ray screening have a false-positive risk of 9 percent after one test and 15 percent after two.
Of the patients who had false positives, Croswell and colleagues said that slightly more than half underwent follow-up imaging exams. In the LDCT group, 6.6 percent of patients with false positives underwent invasive diagnostic procedures and 1.6 percent had major surgery. In the x-ray group, 4.2 percent of patients with false positives underwent invasive follow-up procedures and 1.9 percent of the total patients in this group had major surgery.
Complication rates for patients who had invasive procedures were low, but a few patients had to be hospitalized for a collapsed lung or blood in the lung (less than 1 percent), and another 1 percent had to be given antibiotics for infections, the authors wrote.
They also reported that 6.6 percent of participants with a false-positive LDCT underwent an invasive diagnostic follow-up procedure, 1.6 percent had major surgery; and 4.2 percent of participants with a false-positive chest x-ray underwent an invasive diagnostic follow-up procedure, 1.9 percent had major surgery.
"All medical interventions--including screenings--have not only the potential to benefit patients but also the potential for harm," said Croswell, acting director of the NIH Office of Medical Applications of Research. "We want to give people who are considering lung cancer screening the information they need to make informed decisions about the tests they choose. False-positive results may create increased psychological stress in patients and an increased burden on the healthcare system."
Findings from the study indicated that patients who were current smokers or older than 64 years of age might have an increased risk of false positives, but because the sample sizes were small, the researchers concluded that more studies are needed to confirm the findings.