Impact of lung cancer screening in patients diagnosed with small cell lung cancer.

Abstract

8102 Background: The advent of immunotherapy significantly improved overall survival (OS) for limited-stage SCLC (LS-SCLC), highlighting how early detection may drive maximal therapeutic benefit. Lung cancer screening (LCS) with low-dose CT scans (LDCT) in high-risk individuals reduced the risk of lung cancer mortality and identified more Stage I lung cancer (National Lung Screening Trial (NLST), NELSON). Within the NLST, SCLC distribution by stage (I-IV) was similar between LDCT or chest x-ray, thereby limiting the perceived absolute impact of LCS for SCLC detection. Here, we report on the utility of LCS in SCLC in the era of immunotherapy. Methods: We retrospectively reviewed the charts of patients diagnosed with SCLC in the Indiana University (IU) Health System from 2018 to 2024. Patients were stratified by whether SCLC was identified from LDCT or non-screen detected. Kaplan-Meier, Wilcoxon rank sum, Pearson’s Chi-squared, and Fisher’s exact test were applied. Results: Among the 301 LCS-eligible individuals with SCLC, 67 patients (22.3%) received LDCT preceding their diagnosis. With LDCT, a significant shift in stage was observed ( P <0.001). In the non-LDCT cohort, 28% were diagnosed with LS-SCLC and 72% with ES-SCLC. In the LDCT cohort, 60% were diagnosed with LS-SCLC and 40% with ES-SCLC. After robust adjustment for confounders in a multivariable logistic regression model, LCS was independently associated with higher odds of LS-SCLC at diagnosis (odds ratio 4.22; 95% CI, 2.20-8.28, P <0.001). Significant delays post-LDCT were noted including time from scan to biopsy (52 vs 10 days, P <0.001) and biopsy to treatment (20 vs 13 days, P <0.001). LCS did not improve response rates, treatment completion rates, or progression-free survival, regardless of stage. At diagnosis, patients with ES-SCLC in the LDCT cohort tended to have less CNS involvement (11% vs 30%, P = 0.06) but had more bone metastases (74% vs 45%, P = 0.006), compared to non-LDCT. Survival between LDCT and non-LDCT was similar for LS-SCLC (22.9 vs 40.4 months, P = 0.15) and ES-SCLC (12.2 vs 10.8 months, P = 0.89). To account for stage migration and unequal follow-up between groups (41.4 vs 25.3 months), a pre-specified, stage-agnostic 1-year OS was compared. The LDCT group had a higher 1-year OS compared to the non-LDCT group (69.2% vs 54.6%, P = 0.03). Conclusions: Use of LCS in eligible patients resulted in a significant “stage-shift” to LS-SCLC for individuals diagnosed with SCLC. At a pre-specified cut-off, LCS significantly improved OS for patients diagnosed with SCLC. Characteristic LDCT (No) (n = 234) LDCT (Yes) (n = 67) Overall (n = 301) P value Age (Q1, Q3) 66 (61, 72) 68 (64, 73) 67 (62, 72) 0.1 Sex (female) 145 (62%) 41 (61%) 186 (62%) >0.9 ECOG PS (0-1) 150 (70%) 53 (84%) 203 (73%) 0.024 Current tobacco 171 (73%) 50 (75%) 221 (73%) 0.9 COPD 119 (51%) 48 (72%) 167 (55%) 0.003 +FH cancer 128 (59%) 46 (73%) 174 (62%) 0.047 +FH lung cancer 57 (26%) 22 (35%) 79 (28%) 0.2