The Construction and Validation of Nomogram to Predict the Prognosis with Small-Cell Lung Cancer Followed Surgery

SIMPLE SUMMARY: The therapeutic effect of postoperative radiotherapy for small-cell lung cancer (SCLC) patients with limited stage remained unclear. The aim of this retrospective study was to construct and validate a nomogram to assess the prognosis of small-cell lung cancer patients followed surgery in a large cohort (882 patients) which involved patients from Shanghai Pulmonary Hospital and the Surveillance, Epidemiology and End Results database. The nomogram derived from the training cohort achieved good predictive ability and could discriminate low- and high-risk subgroups in four cohorts. Postoperative radiotherapy promoted survival for high-risk patients but had little effect on low-risk patients. Moreover, by subgroup analysis based on the N stage, we suggested that N2 patients in the high-risk subgroup could benefit more from postoperative radiotherapy. Therefore, our nomogram might help with clinical decisions on the strategy of postoperative radiotherapy for SCLC patients. ABSTRACT: This study constructed and validated a prognostic model to evaluate the survival of small-cell lung cancer (SCLC) patients following surgery, and shed light on the strategy of postoperative radiotherapy. A total of 882 patients from Shanghai Pulmonary Hospital and the Surveillance, Epidemiology and End Results database after lung resection were selected. Multivariable Cox analysis was used to identify the indicators affecting long-term survival in patients. A nomogram was constructed to predict the prognosis of eligible patients. Indices of concordance (C-index) was used to access the predictive ability of cancer-specific survival (CSS) for the prognostic model. CSS discrimination in the prognostic model was comparable in the training and validation cohorts (C-index = 0.637[NORAD-T], 0.660[NORAD-V], 0.656[RAD] and 0.627[our hospital], respectively. Stratification based on the cutoff value of the nomogram yielded low- and high-risk subgroups in four cohorts. For patients in the high-risk group, postoperative radiotherapy was considered a survival-promoting strategy (unadjusted HR 0.641, 95% CI 0.469–0.876, p = 0.0046). In the low-risk group, however, the implementation of radiotherapy barely had an influence on CSS. In conclusion, the nomogram we constructed and validated could predict the prognosis of SCLC patients followed surgery and identify high-risk patients who were likely to benefit from postoperative radiotherapy.