The value of tumor deposits in evaluating colorectal cancer survival and metastasis: a population-based retrospective cohort study

Background The role of tumor deposits (TDs) in TNM staging of colorectal cancer is controversial, especially the relationship with distant metastasis. Purpose This study aimed to determine the effect of TDs on the survival of colorectal cancer and the occurrence of distant metastasis and to determine whether TDs (+) patients behaved similarly to stage IV patients. Methods A retrospective analysis of CRC patients from two large independent cohorts from the Surveillance Epidemiology and End Results (SEER) database (n = 58775) and the First Affiliated Hospital of Dalian Medical University (n = 742). Results Univariate logistic analyses revealed that TDs are an independent predictor of liver metastasis [p < 0.001; odds ratio (OR): 5.738; 95% confidence interval (CI): 3.560-9.248] in the First Affiliated Hospital of Dalian Medical University's patients. Meanwhile, TDs are also an independent predictor of isolated organ metastasis [p <0.001; odds ratio (OR): 3.028; 95% confidence interval (CI): 2.414-3.79; multiple organ metastases [p < 0.001; odds ratio (OR): 4.778; 95% confidence interval (CI): 4.109-5.556]; isolated liver metastasis [p < 0.001; odds ratio (OR): 4.395; 95% confidence interval (CI): 4.099-4.713] and isolated lung metastasis [p < 0.001; odds ratio (OR): 5.738; 95% confidence interval (CI): 3.560-9.248] in the SEER database. Multivariate analyses suggested TDs are an independent poor prognostic factor for distant metastasis (p <0.001). Conclusions Our results have shown that compared with patients with negative TDs, CRC patients with positive TDs are more likely to develop distant metastasis. Patients categorized as T4aN2bM0 TDs (+) and T4bN2M0 TDs (+) have a similar prognosis as those with stage IV, and hence these patients should be classified as stage IV.