A nomogram to predict the recurrence-free survival and analyze the utility of chemotherapy in stage IB non-small cell lung cancer

Background: Large part of patients of stage IB non-small cell lung cancer (IB NSCLC) may suffer recurrence after surgery. This study is to determine risk factors and establish a nomogram for postoperative recurrence and to provide a reference for adjuvant chemotherapy selection in patients with stage IB NSCLC.

Methods: A total of 394 patients with postoperative stage IB NSCLC who visited Fujian Medical University Union Hospital between January 2010 and June 2016 were selected. Patients were divided into training and validation cohorts based on the time of diagnosis. Independent risk factors were identified using a Cox proportional hazards regression model. A nomogram was created to predict recurrence-free survival (RFS) and was validated with an independent cohort. The predictive ability of the nomogram was evaluated using the concordance index (C-index) and calibration curve. RFS between the high- and low-risk groups was determined using Kaplan-Meier curves, and subgroup analysis of chemotherapy was performed.

Results: Visceral pleura invasion, micropapillary structures, tumor size, preoperative serum carcinoembryonic antigen (CEA) level, preoperative serum cytokeratin-19 fragments (Cyfra21-1) level, and postoperative histology were identified as independent risk factors for stage IB NSCLC recurrence. Discrimination of the nomogram showed good prognostic accuracy and clinical applicability, with a C-index of 0.827 and 0.866 in the training and validation cohorts, respectively. The difference in RFS between the high- and low-risk groups in both cohorts was significant (P<0.05). Finally, a significant difference was observed on whether high-risk group should accept postoperative chemotherapy (P<0.05).

Conclusions: This nomogram can predict postoperative recurrence probability in patients with stage IB NSCLC, and can select patients with risk factors who need adjuvant chemotherapy.