Establishment and Validation of a Predictive Nomogram for Postoperative Survival of Stage I Non-Small Cell Lung Cancer

Abstract

Background: Surgical procedure is the preferred option for people with early-stage non-small cell lung cancer (NSCLC), while nearly 30% of patients experienced metastatic or recurrent tumor after operation. The primary intention of this context is to summarize high-risk prognostic factors and set up a novel nomogram to predict the overall survival of individuals with stage I NSCLC after resection.

Methods: Research objects, 10,218 patients with stage I NSCLC after operation from 2010 to 2015, were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Independent prognostic factors, confirmed by Cox regression analyses, were integrated into a nomogram, to predict the 3-and 5-year overall survival of these individuals. The model experienced internal validation of testing cohorts above and external validation crewed by 160 patients from China. Finally, the nomogram was evaluated through several verification methods such as concordance index (C-index), calibration plots and receiver operating characteristic curve (ROC).

Results: Multivariate analysis identified that age, gender, histologic type, differentiation class, type of operation, T stage and treatment were significant predictive factors for the survival of stage I NSCLC. Based on these factors, a nomogram was constructed to predict the 3- and 5-year overall survival of these individuals. Meanwhile, in the training set, this nomogram displayed excellent superiority over the TNM staging system with abroad application, especially in C-index (0.669 vs 0.580) and the AUC (the Area Under ROC Curve) for the 3- and 5-year survival (0.678 vs 0.582; 0.650 vs 0.576). In the calibration curve, the curve representing predicted survival tended to align with the line representing actual survival as well.

Conclusion: A nomogram was successfully created and verified to achieve the goal that made a rounded accurate prediction on the survival of postoperative I NSCLC patients in terms of the SEER database.

Keywords: NSCLC; SEER; nomogram; prognosis; survival.

Figure 1

Flow diagram of the I NSCLC patients with training and validation sets.

Figure 2

Nomogram for predicting 3-year and 5-year overall survival rates. The nomogram adopts the principle of score accumulation, and each factor corresponds to the top “Points” to get a score. The total score “Total Points” obtained by adding the scores of each factor corresponds to “3-years Survival Probability” and “5-years Survival Probability” to get the patient’s 3-year or 5-year survival rate. ADC adenocarcinoma; SC squamous carcinoma; Other large cell carcinoma, adeno squamous carcinoma and so on; Chemo chemotherapy; Rad radiotherapy.

Figure 3

ROC curves of the Nomogram and the TNM stage system for predicting 3-, and 5-year overall survival (OS) (A and B) ROC curves in the training cohort; (C and D) ROC curves in the internal validation cohort; (E and F) ROC curves in the external validation cohort.

Figure 4

Calibration plots of the nomogram for predicting 3-and 5-year OS rates in stage I NSCLC patients. Calibration plots show the relationship between the predicted survival by the model and actual outcomes of training cohort (A), internal validation cohort (B) and external validation cohort (C).