Tumor deposits (TD) of colorectal cancer (CRC) in the 8th edition of TNM classification (TNM 8th) were staged as N1c, but the number of TDs was ignored. The aim of this study was to analyze the association of TD with CRC and verify the rationale for TD staging in the TNM 8th. A total of 517 patients with CRC, surgically treated from Aug. 2013 to Dec. 2017, were retrospectively reviewed. Univariate and multivariate analyses were used to observe the correlations between clinicopathologic features and TD. The reasonability of TD staging in TNM 8th was validated by prognostic analysis. The occurrence of TD in CRC was 11.2% (154/1375). Multivariate analysis indicated that T stage (P<0.001, OR = 2.026 and 5.380, 95% CI: 0.917-4.474 and 2.229-12.981 for T3 and T4 respectively) and TNM stage (P<0.001, OR = 9.051 and 16.305, 95% CI: 2.055-39.857 and 3.780-70.323 for TNM II and TNM III respectively) were independent risk factors for TD status. Only degree of differentiation (P = 0.020, OR = 0.197, 95% CI: 0.050-0.774 for poorly differentiated) was an independent risk factor for number of TDs. Survival analysis showed that patients with TD exhibited a significantly worse prognosis compared to patients without TD (P<0.001), and a significant prognostic difference was found among groups TD = 1, TD = 2/3 and TD≥4 (all P<0.05). Patients in T3-4aN1a/1b had a worse prognosis than patients in T3-4aN1c did, although both groups were classified as TNM IIIB (P = 0.022). TD was an adverse indicator in CRC, and the varying number of TDs represented a classified prognostic factor in CRC. TD staging in the TNM 8th might not be reasonable as it ignores the status and the number of TDs.
Keywords: TNM classification; Tumor deposits; colorectal cancer; prognosis.
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