Among the many studies that have analyzed the MLP data, this study is the first to look at the smoking behavior of the participants. The finding here that smokers in the intervention arm smoked more than those in the control group does not necessarily constitute an argument against lung cancer screening. First, it is not plausible that a difference of one or two cigarettes a day could lead to significantly different health conditions among continuing smokers, and in our study no between-group differences were noted in rates of abstinence. Secondly, we did observe a sizable decline in smoking among all participants after the prevalence lung cancer screening was administered to both groups at baseline. Since it was then that some prevention counseling was given to participants, given what we know about the strong proven effect of counseling on smoking cessation , this large initial decline in smoking could be viewed as evidence supporting the "teachable moment" argument. Still, the fact that participants receiving frequent screening reported significantly higher rates of cigarettes smoked per day might also indicate a paradoxical response to screening. In any case, periodic lung cancer screening appears not to improve long-term abstinence as compared with one-shot screening, a result contrary to what many would have expected but which is consistent with the results reported by Cox et al .
From the viewpoint of "risk compensation" (whereby people adjust their risk behavior to adapt for the changed risk), it is not surprising to see that smokers in the intervention group smoked more cigarettes per day than those in the control group. The human phenomena of behaviorally offsetting exogenous risk modification has been noted and interpreted in different disciplines like economics, psychology and risk analysis [19–22], including studies of smoking behavior [23, 24]. Wilde  proposed a theory of "risk homeostasis" that individuals seek a stable target level of risk to bear and therefore will adjust behavior in response to exogenous changes in risk to maintain that target. Wilde  argues that interventions that have a direct influence on accident cost could successfully alter the target risk level, like countermeasures that increase the benefits associated with accident-free driving and the costs associated with accident involvement. In our context, going through a lung screening program with repeated negative results may conceptually reduce the expected risk of dying from smoking, both by lowering the perceived probability of having lung cancer and by increasing the expected expediency of treatment. Therefore, the expected cost of smoking for participants in the intervention group is lower than for participants in the control group. In other words, the perceived fatal risk of smoking could actually be lowered by repeated negative screening results, and thus lead to more cigarettes smoked per day. Thus, it might be worthwhile to remind smokers undergoing lung cancer screenings that repeated negative results do not imply one's immunity from tobacco-induced lung cancer. Finally, the fact that periodic lung cancer screening neither increased smoking abstinence nor decreased smoking intensity also suggests a need to add smoking cessation interventions into screening programs in order to capitalize on the "teachable moment" in later screenings, as Taylor et al  did in their study. It takes very little time to refer a screened smoker to existent hotline counseling services like the proven tool of Quitline [27, 28].