The Prognostic Significance of Tumor Deposit Count for Colorectal Cancer Patients after Radical Surgery

Abstract

Background: The prognostic value of tumor deposit (TD) count in colorectal cancer (CRC) patients has been rarely evaluated. This study is aimed at exploring the prognostic value of TD count and finding out the optimal cutoff point of TD count to differentiate the prognoses of TD-positive CRC patients.

Method: Patients diagnosed with CRC from Surveillance, Epidemiology, and End Results (SEER) database from January 1, 2010, to December 31, 2012, were analyzed. X-tile program was used to identify the optimal cutoff point of TD count in training cohort, and a validation cohort was used to test this cutoff point after propensity score matching (PSM). Univariate and multivariate Cox proportional hazard models were used to assess the risk factors of survival.

Results: X-tile plots identified 3 (P < 0.001) as the optimal cutoff point of TD count to divide the patients of training cohort into high and low risk subsets in terms of disease-specific survival (DSS). This cutoff point was validated in validation cohort before and after PSM (P < 0.001, P = 0.002). More TD count, which was defined as more than 3, was validated as an independent risk prognostic factor in univariate and multivariate analysis (P < 0.001).

Conclusion: More TD count (TD count ≥ 4) was significantly associated with poor disease-specific survival in CRC patients.

Figure 1

Division of patients in training cohort by the optimal cutoff point for the TD counts produced by X-tile plot. The optimal cutoff point highlighted by the black circle (a) is shown on a histogram of the training cohort (b) and a Kaplan-Meier plot (c). P values were determined using the cutoff point defined in the training cohort and applying it to the validation set. (The optimal cutoff point for TD count is 3, χ² = 21.756, P < 0.001.).

Figure 2

Log-rank tests of DSS comparing patients with TDs (1-3 vs. ≥4) before (a) and after (b) PSM.