Mortality outcomes of low-dose computed tomography screening for lung cancer in urban China: a decision analysis and implications for practice

Abstract

Background: Mortality outcomes in trials of low-dose computed tomography (CT) screening for lung cancer are inconsistent. This study aimed to evaluate whether CT screening in urban areas of China could reduce lung cancer mortality and to investigate the factors that associate with the screening effect.

Methods: A decision tree model with three scenarios (low-dose CT screening, chest X-ray screening, and no screening) was developed to compare screening results in a simulated Chinese urban cohort (100,000 smokers aged 45-80 years). Data of participant characteristics were obtained from national registries and epidemiological surveys for estimating lung cancer prevalence. The selection of other tree variables such as sensitivities and specificities of low-dose CT and chest X-ray screening were based on literature research. Differences in lung cancer mortality (primary outcome), false diagnoses, and deaths due to false diagnosis were calculated. Sensitivity analyses were performed to identify the factors that associate with the screening results and to ascertain worst and optimal screening effects considering possible ranges of the variables.

Results: Among the 100,000 subjects, there were 448, 541, and 591 lung cancer deaths in the low-dose CT, chest X-ray, and no screening scenarios, respectively (17.2% reduction in low-dose CT screening over chest X-ray screening and 24.2% over no screening). The costs of the two screening scenarios were 9387 and 2497 false diagnoses and 7 and 2 deaths due to false diagnosis among the 100,000 persons, respectively. The factors that most influenced death reduction with low-dose CT screening over no screening were lung cancer prevalence in the screened cohort, low-dose CT sensitivity, and proportion of early-stage cancers among low-dose CT detected lung cancers. Considering all possibilities, reduction in deaths (relative numbers) with low-dose CT screening in the worst and optimal cases were 16 (5.4%) and 288 (40.2%) over no screening, respectively.

Conclusions: In terms of mortality outcomes, our findings favor conducting low-dose CT screening in urban China. However, approaches to reducing false diagnoses and optimizing important screening conditions such as enrollment criteria for screening are highly needed.

Keywords: Decision analysis; Low-dose CT; Lung cancer; Mortality outcome; Screening.

Fig. 1

Decision tree model for the analysis of lung cancer mortality, false positive diagnosis, and death due to false diagnosis with low-dose computed tomography (CT) screening and no screening. Chest X-ray screening is similar to low-dose CT screening and is not shown. prev lung cancer prevalence in the screened cohort, CTse sensitivity of low-dose CT, CTsp specificity of low-dose CT, CTerl proportion of early-stage cancers among lung cancers detected with low-dose CT, NSerl proportion of early-stage cancers among lung cancers detected with no screening, fpMt death possibility due to false diagnosis and invasive treatment, trt_Er acceptance rate of surgery for individuals with early-stage lung cancers, trt_Ne acceptance rate of surgery for individuals with non-early-stage lung cancers, srv_Er survival possibility of individuals with resected early-stage lung cancer, CTidl proportion of indolent cancers among lung cancers detected with low-dose CT, srv_Ne survival possibility of individuals with resected non-early-stage lung cancer

Fig. 2

Tornado histogram of lung cancer deaths in the low-dose CT screening scenario over the no screening scenario. EV effect value, horizontal line represents the relative difference in lung cancer deaths with low-dose CT screening over no screening (the higher the EV, the higher the screening benefits), and vertical dash line indicates the location of estimated average EV, prev lung cancer prevalence in the screened cohort, CTse sensitivity of low-dose CT, CTerl proportion of early-stage cancers among lung cancers detected with low-dose CT, srv_Er survival possibility of patients with resected early-stage lung cancers, NSerl proportion of early-stage cancers among lung cancers detected with no screening, CTidl proportion of indolent cancers among lung cancers detected with low-dose CT, fpMt death possibility due to false diagnosis and invasive treatment, srv_Ne survival possibility of individuals with resected non-early-stage lung cancer, trt_Er acceptance rate of surgery for early-stage lung cancers, CTsp specificity of low-dose CT, trt_Ne acceptance rate of surgery for non-early-stage lung cancers. Asterisk the proportion of difference squared between low and high EV for each variable of the sum of differences squared for all variables. The plus sign denotes that the higher the variable value, the greater the reduction in lung cancer deaths with low-dose CT screening over no screening, and the minus sign denotes that the higher the variable value, the smaller the reduction in lung cancer deaths with low-dose CT screening over no screening

Fig. 3

Reductions in lung cancer deaths with low-dose CT screening over chest X-ray screening and no screening among men and women of 45–80 years old with different proportions of smokers. Bars represent absolute reduction in deaths; dotted lines represent relative reduction in deaths. Red low-dose CT over chest X-ray screening for men, yellow low-dose CT over chest X-ray screening for women, blue low-dose CT over no screening for men, green low-dose CT over no screening for women. Asterisk lung cancer prevalence among the screened population, per 100,000