Short-term quantitative CT trajectories of pulmonary Ground-Glass nodules during immune checkpoint inhibitor Therapy: A matched surveillance cohort study.

BACKGROUND

The short-term CT behavior of pulmonary ground-glass nodules (GGNs) during immune checkpoint inhibitor (ICI) therapy remains uncertain. We compared longitudinal CT changes in GGNs observed during ICI therapy with those in a matched surveillance cohort of untreated GGNs.

METHODS

In this retrospective exploratory study, the ICI cohort was identified from 1,930 patients with malignant tumors and synchronous pulmonary nodules. After eligibility screening, 98 patients with one target GGN per patient were included, and 80 patients entered the patient-level matched analysis. The comparator cohort was derived from individuals with incidentally detected GGNs on health screening CT, and 80 matched controls were included. Baseline and follow-up CT scans were assessed for changes in diameter, volume, CT attenuation, and solid component proportion. Monthly change rates and multivariable analyses were used to evaluate volume change and progression.

RESULTS

In the matched cohort, GGNs in the ICI group showed a decrease in diameter, whereas control GGNs showed increases in both diameter and volume. Compared with controls, the ICI group had lower monthly rates of change in diameter (-0.062 vs 0.048 mm/month; FDR < 0.001) and volume (-0.855 vs 2.425 mm3/month; FDR = 0.001). In multivariable analysis, ICI-group assignment remained associated with a lower Δvolume rate (β = -11.28, 95% CI -22.34 to -0.23; p = 0.046) and lower odds of volumetric progression (OR = 0.43, 95% CI 0.19-0.93; p = 0.037).

CONCLUSIONS

ICI-treated GGNs showed different short-term quantitative CT trajectories compared with untreated ones, particularly lower monthly growth in diameter and volume. However, these observational findings should be interpreted as associations rather than causal treatment effects.