Table 2:
Effect of features noted on an abnormal LDCT screen on risk of immediate lung cancer among participants in the National Lung Screening Trial: the immediate risk component of the LCRAT+CTpos model
| Immediate lung cancer detection risk = r0(x)y with exponent y for pre-screening risk r0 calculated as follows: |
Prevalence of feature | Median risk among individuals with the feature (IQR) | |
|---|---|---|---|
|
| |||
| What was the longest diameter among all nodules? | This gives the initial value: | ||
| N/A* | 0.60 (0.52–0.69) | 2.5% | 4.1% (3.0–5.4%) |
| 4–5mm | 1.01 (0.92–1.10) | 35.7% | 0.26% (0.14–0.47%) |
| 6–7mm | 0.82 (0.75–0.89) | 28.3% | 0.72% (0.39–1.4%) |
| 8–10mm | 0.64 (0.58–0.70) | 17.2% | 2.4% (1.3–4.3%) |
| 11–13mm | 0.50 (0.44–0.57) | 6.6% | 6.2% (3.7–11.0%) |
| 14mm or greater | 0.40 (0.35–0.46) | 9.8% | 9.8% (8.2–25.8%) |
| Was any nodule in the upper lobes? | If yes, subtract 0.08 (0.05–0.11) | 47.0% | 1.2% (0.43–4.6%) |
| Was any nodule in the right middle lobe or lingula? | If yes, add 0.05 (0.01–0.09) | 25.5% | 0.55% (0.21–1.8%) |
| Prevalence screen: did any nodule have spiculated margins? | If yes, subtract 0.27 (0.22–0.31) | 13.7% | 11.1% (3.3–27.6%) |
| Incidence screen(s), did any nodule have spiculated margins? | If yes, subtract 0.12 (0.08–0.16) | 10.8% | 5.8% (1.6–17.1%) |
| Did any nodule have indeterminate margins? | If yes, subtract 0.07 (0.04–0.11) | 30.3% | 2.0% (0.92–3.9%) |
| If incidence screen(s), were any new nodules present? | If yes, subtract 0.05 (0.02–0.09) | 41.6% | 1.1% (0.38–4.1%) |
| If incidence screen(s), did any nodule show interval growth? | If yes, subtract 0.17 (0.13–0.20) | 9.8% | 8.8% (3.6–20.0%) |
| Were there any ground-glass nodules? | If yes, add 0.11 (0.07–0.15) | 18.8% | 1.0% (0.31–3.5%) |
| Were there any micronodules? | If yes, add 0.05 (0.02–0.08) | 38.6% | 0.59% (0.23–2.0%) |
| Is the participant female? | If yes, subtract 0.04 (0.01–0.06) | 41.5% | 0.83% (0.30–3.0%) |
| Is the participant overweight or obese (BMI>25)? | If yes, subtract 0.03 (0.01–0.06) | 69.7% | 0.75% (0.27–2.7%) |
| Compute the natural log of one plus the number of nodules | Multiply by 0.15 (0.10–0.19) and then add to total exponent | Mean # of nodules: 1.68 | For screen with 1 nodule†: 0.72% (0.28–2.5%) |
The formula r0(x)y calculates immediate lung cancer detection risk as the pre-screening risk r0 based on individual covariates x (i.e., r0(x)), raised to an exponent y which is calculated as described in the table. Note that lower numbers imply higher risk and subtracting increases risk. Pre-screening risk r0 refers to 1-year lung cancer risk calculated by LCRAT. Number of nodules and micronodules appear to reduce risk because many predictors increase risk if any nodule has that feature, so these factors “standardize” for multiple chances to have a deleterious feature. The prevalence and risks for nodule features are calculated using data from all screens.
Screen was positive for a reason (i.e., suspicious abnormalities) other than a nodule ≥4 mm
Median number of nodules found on a screen was 1 (59.5% of screens had 1 nodule only).