Lung cancer CT screens could save 12,000 lives

Roughly 12,250 deaths could be delayed or prevented each year if a national lung cancer computed tomography screening program were implemented among heavy smokers in the United States.

That represents about 7.6% of all lung cancer deaths in the nation, according to a new study led by Jiemin Ma, Ph.D., a senior epidemiologist in surveillance research with the American Cancer Society (Cancer 2013 Feb. 25 [doi: 10.1002/cncr.27813]).

To make the calculation, the authors used the most recently available National Health Interview Survey and 2010 U.S. Census data, and applied the National Lung Screening Trial (NLST) criteria of patients aged 55-74 years with at least 30 pack-years of smoking who were still smoking or had quit in the last 15 years.

The landmark NLST demonstrated a 20% reduction in lung cancer mortality over 6.5 years using low-dose computed tomography (LDCT) screening versus chest radiography (N. Engl. J. Med. 2011;365:395-409). That study sparked debate about how – or even if – a national lung cancer screening program should be implemented.

The authors of the current study estimated that 8.6 million Americans would be eligible for LDCT screening. That’s up from 7 million identified in the NLST.

Several factors might have affected the new estimates, including use of the NLST-reported screening effect as a parameter in determining the number of avertable lung cancer deaths.

Although this approach is "straightforward and easy to understand," direct use of the NLST screening effect "confines our estimates to be interpreted within the context of the NLST study design and screening protocol," the authors wrote.

The NLST did not address the effectiveness of screening in patients with fewer pack-years or starting at an earlier age, and the study’s investigators noted that the 20% mortality reduction with LDCT screening may be an underestimated effect.

Dr. Ma also pointed out that the NLST used chest x-ray (CXR) for its control group, something unlikely to occur in the general population. This potentially also could lead to an underestimation of avertable lung cancer deaths "if CXR was of benefit in preventing lung cancer mortality," he said.

Other factors that may have led to underestimation include the use of self-reported smoking data, which can be a bit unreliable because smokers tend to underreport their tobacco use.

On the other hand, the lung cancer mortality rates for screening-eligible populations were estimated based on deaths occurring between 2000 and 2006, possibly overestimating the current rates, the authors observed.

The model also assumed that 100% of the target population would undergo screening, which is unlikely to be achieved in the real world.

Under an optimal scenario of 100% screening uptake and a 30% reduction in lung cancer death rates, 18,375 lung cancer deaths would be averted each year by LDCT screening, Dr. Ma reported. If just 70% of the 8.6 million eligible people are screened annually, however, the number of lung cancer deaths averted falls to 8,575.

"Ultimately, the magnitude of potential benefit from LDCT screening in the community remains to be determined," he wrote.

The American Cancer Society and American Lung Association back screening for heavy smokers based on the NLST criteria, while National Comprehensive Cancer Network (NCCN) surveillance guidelines are somewhat broader and include smokers aged 50 years or older with a smoking history of 20 pack-years plus an additional lung cancer risk factor.

In an accompanying editorial titled "Is 20% of a Loaf Enough?" Larry Kessler, Sc.D., cautioned against "haphazard adoption" of LDCT outside of organized and clear screening protocols, citing such potential harms as inconsistent follow-up with providers and the fear generated by false positives (Cancer 2013 Feb. 25 [doi: 10.1002/cncr.27811]). In NLST, 24.2% of LDCT scans were positive, and 96.4% of those positive results were false-positive findings, noted Dr. Kessler, chair of health services at the University of Washington in Seattle.

While the new national "estimates are important," the approach taken by the investigators "missed some critical elements of population dynamics that may alter what we would really experience with a nationally organized screening program," he cautioned.

First, the study reported 1-year estimates instead of the more common life-years saved approach, which is necessary to appreciate the effect of the screening program over time.

"The likely effect is that Ma et al. may have underestimated the total effect over time of a national CT screening program," Dr. Kessler said.

He also suggested the analysis failed to address the dynamics of smoking, which are influenced by age, period, and cohort effects – and must be tied to estimating the long-term effect of a screening program. An obvious example of that is the alarming increase in smoking among women, Dr. Kessler noted, which would alter the discrepancy in lung cancer deaths between the sexes, because the smoking histories of women ultimately "catch up."

Of the 5.2 million men and 3.4 million women eligible for screening, an estimated 8,990 deaths in men and 3,260 deaths in women would be averted with LDCT screening, according to the study’s analysis.

The study was supported by the Intramural Research Department of the American Cancer Society. Dr. Ma, his coauthors, and Dr. Kessler made no disclosures.

p.wendling@elsevier.com

Roughly 12,250 deaths could be delayed or prevented each year if a national lung cancer computed tomography screening program were implemented among heavy smokers in the United States.

That represents about 7.6% of all lung cancer deaths in the nation, according to a new study led by Jiemin Ma, Ph.D., a senior epidemiologist in surveillance research with the American Cancer Society (Cancer 2013 Feb. 25 [doi: 10.1002/cncr.27813]).

To make the calculation, the authors used the most recently available National Health Interview Survey and 2010 U.S. Census data, and applied the National Lung Screening Trial (NLST) criteria of patients aged 55-74 years with at least 30 pack-years of smoking who were still smoking or had quit in the last 15 years.

The landmark NLST demonstrated a 20% reduction in lung cancer mortality over 6.5 years using low-dose computed tomography (LDCT) screening versus chest radiography (N. Engl. J. Med. 2011;365:395-409). That study sparked debate about how – or even if – a national lung cancer screening program should be implemented.

The authors of the current study estimated that 8.6 million Americans would be eligible for LDCT screening. That’s up from 7 million identified in the NLST.

Several factors might have affected the new estimates, including use of the NLST-reported screening effect as a parameter in determining the number of avertable lung cancer deaths.

Although this approach is "straightforward and easy to understand," direct use of the NLST screening effect "confines our estimates to be interpreted within the context of the NLST study design and screening protocol," the authors wrote.

The NLST did not address the effectiveness of screening in patients with fewer pack-years or starting at an earlier age, and the study’s investigators noted that the 20% mortality reduction with LDCT screening may be an underestimated effect.

Dr. Ma also pointed out that the NLST used chest x-ray (CXR) for its control group, something unlikely to occur in the general population. This potentially also could lead to an underestimation of avertable lung cancer deaths "if CXR was of benefit in preventing lung cancer mortality," he said.

Other factors that may have led to underestimation include the use of self-reported smoking data, which can be a bit unreliable because smokers tend to underreport their tobacco use.

On the other hand, the lung cancer mortality rates for screening-eligible populations were estimated based on deaths occurring between 2000 and 2006, possibly overestimating the current rates, the authors observed.

The model also assumed that 100% of the target population would undergo screening, which is unlikely to be achieved in the real world.

Under an optimal scenario of 100% screening uptake and a 30% reduction in lung cancer death rates, 18,375 lung cancer deaths would be averted each year by LDCT screening, Dr. Ma reported. If just 70% of the 8.6 million eligible people are screened annually, however, the number of lung cancer deaths averted falls to 8,575.

"Ultimately, the magnitude of potential benefit from LDCT screening in the community remains to be determined," he wrote.

The American Cancer Society and American Lung Association back screening for heavy smokers based on the NLST criteria, while National Comprehensive Cancer Network (NCCN) surveillance guidelines are somewhat broader and include smokers aged 50 years or older with a smoking history of 20 pack-years plus an additional lung cancer risk factor.

In an accompanying editorial titled "Is 20% of a Loaf Enough?" Larry Kessler, Sc.D., cautioned against "haphazard adoption" of LDCT outside of organized and clear screening protocols, citing such potential harms as inconsistent follow-up with providers and the fear generated by false positives (Cancer 2013 Feb. 25 [doi: 10.1002/cncr.27811]). In NLST, 24.2% of LDCT scans were positive, and 96.4% of those positive results were false-positive findings, noted Dr. Kessler, chair of health services at the University of Washington in Seattle.

While the new national "estimates are important," the approach taken by the investigators "missed some critical elements of population dynamics that may alter what we would really experience with a nationally organized screening program," he cautioned.

First, the study reported 1-year estimates instead of the more common life-years saved approach, which is necessary to appreciate the effect of the screening program over time.

"The likely effect is that Ma et al. may have underestimated the total effect over time of a national CT screening program," Dr. Kessler said.

He also suggested the analysis failed to address the dynamics of smoking, which are influenced by age, period, and cohort effects – and must be tied to estimating the long-term effect of a screening program. An obvious example of that is the alarming increase in smoking among women, Dr. Kessler noted, which would alter the discrepancy in lung cancer deaths between the sexes, because the smoking histories of women ultimately "catch up."

Of the 5.2 million men and 3.4 million women eligible for screening, an estimated 8,990 deaths in men and 3,260 deaths in women would be averted with LDCT screening, according to the study’s analysis.

The study was supported by the Intramural Research Department of the American Cancer Society. Dr. Ma, his coauthors, and Dr. Kessler made no disclosures.

p.wendling@elsevier.com

Roughly 12,250 deaths could be delayed or prevented each year if a national lung cancer computed tomography screening program were implemented among heavy smokers in the United States.

That represents about 7.6% of all lung cancer deaths in the nation, according to a new study led by Jiemin Ma, Ph.D., a senior epidemiologist in surveillance research with the American Cancer Society (Cancer 2013 Feb. 25 [doi: 10.1002/cncr.27813]).

To make the calculation, the authors used the most recently available National Health Interview Survey and 2010 U.S. Census data, and applied the National Lung Screening Trial (NLST) criteria of patients aged 55-74 years with at least 30 pack-years of smoking who were still smoking or had quit in the last 15 years.

The landmark NLST demonstrated a 20% reduction in lung cancer mortality over 6.5 years using low-dose computed tomography (LDCT) screening versus chest radiography (N. Engl. J. Med. 2011;365:395-409). That study sparked debate about how – or even if – a national lung cancer screening program should be implemented.

The authors of the current study estimated that 8.6 million Americans would be eligible for LDCT screening. That’s up from 7 million identified in the NLST.

Several factors might have affected the new estimates, including use of the NLST-reported screening effect as a parameter in determining the number of avertable lung cancer deaths.

Although this approach is "straightforward and easy to understand," direct use of the NLST screening effect "confines our estimates to be interpreted within the context of the NLST study design and screening protocol," the authors wrote.

The NLST did not address the effectiveness of screening in patients with fewer pack-years or starting at an earlier age, and the study’s investigators noted that the 20% mortality reduction with LDCT screening may be an underestimated effect.

Dr. Ma also pointed out that the NLST used chest x-ray (CXR) for its control group, something unlikely to occur in the general population. This potentially also could lead to an underestimation of avertable lung cancer deaths "if CXR was of benefit in preventing lung cancer mortality," he said.

Other factors that may have led to underestimation include the use of self-reported smoking data, which can be a bit unreliable because smokers tend to underreport their tobacco use.

On the other hand, the lung cancer mortality rates for screening-eligible populations were estimated based on deaths occurring between 2000 and 2006, possibly overestimating the current rates, the authors observed.

The model also assumed that 100% of the target population would undergo screening, which is unlikely to be achieved in the real world.

Under an optimal scenario of 100% screening uptake and a 30% reduction in lung cancer death rates, 18,375 lung cancer deaths would be averted each year by LDCT screening, Dr. Ma reported. If just 70% of the 8.6 million eligible people are screened annually, however, the number of lung cancer deaths averted falls to 8,575.

"Ultimately, the magnitude of potential benefit from LDCT screening in the community remains to be determined," he wrote.

The American Cancer Society and American Lung Association back screening for heavy smokers based on the NLST criteria, while National Comprehensive Cancer Network (NCCN) surveillance guidelines are somewhat broader and include smokers aged 50 years or older with a smoking history of 20 pack-years plus an additional lung cancer risk factor.

In an accompanying editorial titled "Is 20% of a Loaf Enough?" Larry Kessler, Sc.D., cautioned against "haphazard adoption" of LDCT outside of organized and clear screening protocols, citing such potential harms as inconsistent follow-up with providers and the fear generated by false positives (Cancer 2013 Feb. 25 [doi: 10.1002/cncr.27811]). In NLST, 24.2% of LDCT scans were positive, and 96.4% of those positive results were false-positive findings, noted Dr. Kessler, chair of health services at the University of Washington in Seattle.

While the new national "estimates are important," the approach taken by the investigators "missed some critical elements of population dynamics that may alter what we would really experience with a nationally organized screening program," he cautioned.

First, the study reported 1-year estimates instead of the more common life-years saved approach, which is necessary to appreciate the effect of the screening program over time.

"The likely effect is that Ma et al. may have underestimated the total effect over time of a national CT screening program," Dr. Kessler said.

He also suggested the analysis failed to address the dynamics of smoking, which are influenced by age, period, and cohort effects – and must be tied to estimating the long-term effect of a screening program. An obvious example of that is the alarming increase in smoking among women, Dr. Kessler noted, which would alter the discrepancy in lung cancer deaths between the sexes, because the smoking histories of women ultimately "catch up."

Of the 5.2 million men and 3.4 million women eligible for screening, an estimated 8,990 deaths in men and 3,260 deaths in women would be averted with LDCT screening, according to the study’s analysis.

The study was supported by the Intramural Research Department of the American Cancer Society. Dr. Ma, his coauthors, and Dr. Kessler made no disclosures.

p.wendling@elsevier.com