CT screening averted more lung cancer deaths than CXR in current versus former smokers (8.3 vs 2.4 per 1000), but this benefit was offset by excess cardiovascular deaths (+23 vs +9 per 1000).
RCT (n=18,463)
Yes
Does lung cancer screening with CT compared to CXR affect cause-specific mortality differently in current versus former smokers?
The mortality benefit of lung cancer screening with CT in current smokers is offset by a higher rate of competing cardiovascular and other cancer deaths, highlighting the critical need for smoking cessation.
Absolute Event Rate: 8.3% vs 2.4%
Abstract Rationale There is a growing appreciation that the reduction in lung cancer (LC) deaths attributed to lung cancer screening (LCS) may be attenuated by competing deaths. These deaths include from cardiovascular, respiratory and other cancers. This concern is magnified by the recent studies indicating those currently undergoing LCS are older and have greater comorbid diseases which predispose them to competing deaths. One important contributor to these non-lung cancer (competing) deaths is continued smoking during screening. Aim This study aimed to compare LCS outcomes with respect to smoking status and its effect on both LC deaths and non-lung cancer deaths, to assess the overall difference in mortality by screening arm. Methods In a secondary analysis from the National Lung Screening Trial (N = 18,463), where cause-specific mortality was a primary endpoint and adjudicated in 97% of all deaths, we compared mortality in current versus former smokers according to screening arm. LCS efficacy was calculated as the LC deaths averted per 1000 screened (CT vs CXR). Results We found in our high risk older ever smokers (55-74 yrs, 30+ pack years and current smokers or quit15 yrs), that 50% were still smoking at baseline (N = 9,288). In this current smoking group, while LC cases were comparable according to screening arm, the number of lung cancer deaths averted per 1000 screened (favouring CT over CXR) was 8.3 versus 2.4 in former smokers. However, this greater LCS efficacy in current smokers was undermined due to excess cardiovascular deaths (+23/1000 vs + 9/1000 in former smokers) and excess non-LC deaths (+23/1000 vs -2/1000 in former smokers) (Table 1). Conclusion Our results suggest that while LCS efficacy is greater in those still smoking, relative to former smokers, this apparent benefit is off-set by a greater number of cardiovascular and other cancer deaths in those randomised to CT. In population attributable risk analyses “current smoking” has been shown to be one of the most influential contributors (along with male gender) to these deaths (greater than age and pack years). We conclude that due to the effects of competing deaths, LCS participants should be strongly supported to quit to gain greater benefit from LCS. This supports other analyses suggesting lung cancer mortality itself can be effectively reduced by quitting smoking, in addition to benefits conferred by the screening process. This abstract is funded by: None
Scott et al. (Fri,) conducted a rct in Lung cancer screening (n=18,463). CT screening vs. CXR screening was evaluated on Lung cancer deaths averted per 1000 screened (CT vs CXR) in current vs former smokers. CT screening averted more lung cancer deaths than CXR in current versus former smokers (8.3 vs 2.4 per 1000), but this benefit was offset by excess cardiovascular deaths (+23 vs +9 per 1000).