Development and validation of two prognostic nomograms for predicting survival in patients with non-small cell and small cell lung cancer

Abstract

Purpose: This study aimed to construct two prognostic nomograms to predict survival in patients with non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) using a novel set of clinical parameters.

Patients and methods: Two nomograms were developed, using a retrospective analysis of 5384 NSCLC and 647 SCLC patients seen during a 10-year period at Xiang Ya Affiliated Cancer Hospital (Changsha, China). The patients were randomly divided into training and validation cohorts. Univariate and multivariate analyses were used to identify the prognostic factors needed to establish nomograms for the training cohort. The model was internally validated via bootstrap resampling and externally certified using the validation cohort. Predictive accuracy and discriminatory capability were estimated using concordance index (C-index), calibration curves, and risk group stratification.

Results: The largest contributor to overall survival (OS) prognosis in the NSCLC nomogram was the therapeutic regimen and diagnostic method parameters, and in the SCLC nomogram was the therapeutic regimen and health insurance plan parameters. Calibration curves for the nomogram prediction and the actual observation were in optimal agreement for the 3-year OS and acceptable agreement for the 5-year OS in both training datasets. The C-index was higher for the NSCLC cohort nomogram than for the TNM staging system (0.67 vs. 0.64, P = 0.01) and higher for the SCLC nomogram than for the clinical staging system (limited vs. extensive) (0.60 vs. 0.53, P = 0.12).

Conclusion: Treatment regimen parameter made the largest contribution to OS prognosis in both nomograms, and these nomograms might provide clinicians and patients a simple tool that improves their ability to accurately estimate survival based on individual patient parameters rather than using an averaged predefined treatment regimen.

Keywords: external validation; nomograms; non-small-cell lung cancer; small-cell lung cancer; treatment regimen.

Figure 1

Prognostic nomograms for patients with (A) non-small-cell lung cancer and (B) small-cell lung cancer. CE, company employee; EE, enterprise worker; F, freelance; Fa, farmer; NRC, new rural cooperative medical scheme; PSE, public sector employee; F or S, freelance or self-employed; Self, self-pay; UEB, urban employees basic medical insurance; URB, urban residents basic medical insurance. Treatment regimens: C, simple chemotherapy; R, simple radiotherapy; RC, chemotherapy/radiotherapy; S, simple surgery, SC, surgery/chemotherapy; SR, surgery/radiotherapy; SRC, surgery/chemotherapy/radiotherapy. Differentiation: 1, High; 2, Moderate; 3, Low; 4, Unkown.

Figure 2

The calibration curves for predicting survival of patients with non-small-cell lung cancer at (a) 3 years and (b) 5 years in the primary cohort, and at (c) 3 years in the validation cohort; and for predicting survival of patients with small-cell lung cancer at (d) 3 years and (e) at 5 years in the primary cohort, and at (f) 3 years s in the validation cohort. The nomogram-predicted probability of the overall survival (OS) is plotted on the x-axis. The actual OS is plotted on the y-axis.

Figure 3

Risk group stratification within each TNM stage (A) in the primary cohort (a, all patients; b-e, stages) and (B) in the validation cohort of the NSCLC patients (a, all patients; b-e, stages) NSCLC, non-small-cell lung cancer; SCLC, small-cell lung cancer; TNM, tumor-node-metastasis.

Figure 4

The risk group stratification within each clinical stage in the primary cohort (a, all patients; b-c, stages) and in the validation cohort of the SCLC patents (d, all patients; e-f, stages) NSCLC, non-small-cell lung cancer; SCLC, small-cell lung cancer.