Exploration of a novel prognostic model based on nomogram in non-small cell lung cancer patients with distant organ metastasis: implications for immunotherapy

Background: Evidence for the effects of immunotherapy in non-small cell lung cancer (NSCLC) patients with distant organ metastasis is insufficient, and the predictive efficacy of established markers in tissue and blood is elusive. Our study aimed to determine the prognostic factors and develop a survival prognosis model for these patients.Methods: A total of 100 advanced NSCLC patients with distant organ metastases, who received single or combination immune checkpoint inhibitors (ICIs) in Xijing Hospital between June 2018 and June 2021, were enrolled for retrospective analysis. The major clinicopathological parameters were collected, and associated survival outcomes were followed up by telephone or inpatient follow-up for nearly 3 years to assess prognoses. The survival prognosis model was established based on univariate and multivariate Cox regression analyses to determine the candidate prognostic factors.Results: From the start of immunotherapy to the last follow-up, 77 patients progressed and 42 patients died, with a median follow-up of 18 months [95% confidence interval (CI): 15-19.9]. The median progression-free survival (PFS) and overall survival (OS) were 8 months (95% CI: 5.6-10.4) and 21 months (95% CI: 8.9-33.1), respectively. Multivariate Cox proportional hazards analysis showed Eastern Cooperative Oncology Group performance status (ECOG PS), body mass index (BMI), age-adjusted Charlson comorbidity index (ACCI), lactate dehydrogenase (LDH), and absolute neutrophil count (ANC) were correlated significantly with OS. Based on these five predictive factors, a nomogram and corresponding dynamic web page were constructed with a concordance index (C-index) of 0.81 and a 95% CI of 0.778-0.842. Additionally, the calibration plot and time-receiver operating characteristic (ROC) curve validated the precision of the model at 6-, 12-, and 18-month area under the curves (AUCs) reached 0.934, 0.829, and 0.846, respectively. According to the critical point of the model, patients were further divided into a high-risk total point score (TPS) >258, middle-risk (204< TPS 5258), and low-risk group (TPS 5204), and significant OS differences were observed among the three subgroups (median OS: 4.8 vs. 13.0 vs. 32.9 months).Conclusions: A feasible and practical model based on clinical characteristics has been developed to predict the prognosis of NSCLC patients with distant organ metastasis undergoing immunotherapy.