Development and validation of a CT-based radiomics nomogram for predicting progression-free survival in patients with small cell lung cancer

Abstract

Purpose: Small cell lung cancer (SCLC) is a highly aggressive form of lung cancer, representing about 15% of cases worldwide. Despite advances in imaging, such as low-dose CT, which have increased diagnostic rates, survival outcomes for SCLC patients have remained stagnant. Recent studies have only focused on radiomics, which extracts detailed quantitative features from imaging, with clinical risk factors to improve prognostic models. Therefore, this study aimed to develop a clinical-radiomics fusion nomogram based on computed tomography (CT) to estimate progression-free survival (PFS) in patients diagnosed with SCLC. By integrating radiomics features extracted from CT with clinical data, this model provides personalized prognostic assessment for clinicians. Its clinical utility lies in aiding treatment decision-making by offering more accurate prognostic evaluation, optimizing therapeutic strategies, and identifying high-risk patients at an early stage, ultimately improving overall survival and quality of life.

Methods: To develop the nomogram model, 95 patients diagnosed with pathologically confirmed SCLC between January 1, 2013, and December 31, 2023, were included in the study cohort. Participants were randomly divided into training and validation cohorts in a 7:3 ratio. Radiomics features associated with PFS were generated using the least absolute shrinkage and selection operator (LASSO) along with univariate and multivariate analyses. Additionally, in the training cohort, both univariate and multivariate analyses using Cox regression were conducted to identify the significant clinical risk factors influencing PFS. The predictive performance of the clinical and clinical-radiomics fusion nomogram were evaluated using the concordance index, calibration plots, and decision curve analysis (DCA).

Results: Five radiomics features were selected and used to calculate the radiomics score (Rad-score). The radiomics features were significantly associated with PFS (hazard ratio: 0.5765, 95% confidence interval: 0.3641-0.9128, p < 0.05). Three clinical risk factors significantly associated with PFS were identified: neuron-specific enolase (NSE), carbohydrate antigen 125 levels (CA125), and treatment type, such as surgery. The clinical-radiomics fusion nomogram model (C-index:0.744) demonstrated superior performance compared to the clinical nomogram model (C-index: 0.718) in the training cohort. DCA indicated that the clinical-radiomics fusion nomogram outperformed the clinical nomogram in terms of clinical usefulness.

Conclusions: A CT-based clinical-radiomics fusion nomogram was developed to predict PFS in patients with SCLC, which is useful in providing individualized information.

Advances in knowledge: A clinical-radiomics fusion nomogram was constructed to estimate the probability of PFS based on clinical risk factors and the rad-score.

Keywords: Computed tomography; Nomogram; Progression-free survival; Radiomics; Small-cell lung cancer.

Fig. 1

Study workflow diagram. Lasso = least absolute shrinkage and selection operator, ROC = receiver operating characteristic curve, DCA = decision curve analysis

Fig. 2

The radiomics flow chart of the study. (a) VOI segmentation (b) Features selection including lasso Coefficient path diagram, lasso Regression analysis cross plot, the correlation heatmap (c) nomogram construction including clinical nomogram and clinical-radiomics nomogram (d) nomogram validation including DCA, calibration curve and ROC

Fig. 3

(a) clinical nomogram (b) clinical-radiomics fusion nomogram

Fig. 4

(a) Kaplan-Meier progression-free survival (PFS) curves of patients at different risks stratified by the Rad-score in the training cohort. (b) decision curve analysis for each nomogram in the training cohort. The y-axis measures the net benefit. The clinical-radiomics nomogram (solid blue line) had a higher net benefit compared with the clinical nomogram (red dotted line)

Fig. 5

The ROC curves for the training and validation cohorts. (a) training cohort for clinical nomogram. (b)validation cohort for clinical nomogram. (c) training cohort for clinical-radiomics nomogram. (d) validation cohort for clinical-radiomics nomogram

Fig. 6

Plot shows a calibration of the clinical nomogram and clinical-radiomics nomogram in terms of agreement between predicted and observed 6-, and 12-months PFS outcomes in the training cohort. (a) 6-month calibration curves for clinical nomogram. (b) 12-month calibration curves for clinical nomogram. (c) 6-month calibration curves for clinical-radiomics nomogram. (d) 12-month calibration curves for clinical-radiomics nomogram