Prognostic Significance of Tumor Deposits in Patients With Stage III Colon Cancer: A Nomogram Study

Abstract

Background: The clinical characteristics of stage III colon cancer and the prognostic significance of tumor deposits were investigated, to construct a prognostic nomogram.

Methods: The data of patients were retrieved from the Surveillance, Epidemiology, and End Results database. Patients were randomized to a training or validation cohort. The Kaplan-Meier method was used to analyze survival rates. In the training cohort, a prognostic nomogram was established via Cox regression and then tested in the validation cohort. The accuracy and discrimination of the nomogram were assessed using concordance indices (C-indices) and calibration curves.

Results: Of the 9246 patients meeting the inclusion criteria, 1788 (19.3%) had tumor deposits. Patients with tumor deposits only showed similar survival rates to those with lymph node metastases only (P = 0.83). Compared with these, patients with both tumor deposits and lymph node metastases exhibited significantly worse survival (P < 0.01). In the multivariate Cox regression analyses, the following were identified as independent prognostic indicators and adopted to formulate the nomogram: tumor deposits, age, ethnicity, T stage, the number of positive regional lymph nodes, grade, and carcinoembryonic antigen. In the training cohort, the calibration curve showed good consistency, and the concordance index of the nomogram for predicting overall survival reaches 0.727 (95% CI: 0.71524-0.73876), superior to the concordance index of the American Joint Committee on Cancer staging system (0.594, 95% CI: 0.58224-0.60576). These results are supported in the validation cohort.

Conclusions: Tumor deposits may be an independent prognostic factor for patients with stage III colon cancer after colectomy. The nomogram constructed herein accurately predicted overall survival.

Keywords: Colon cancer; Lymph node metastasis; Nomogram; Prognosis; Survival; Tumor deposit.