Prognostic Significance of Tumor Deposits in Stage III Colon Cancer

The American Joint Committee on Cancer includes extranodal tumor deposits in the tumor-node-metastasis classification of colon cancer. However, it is unclear how tumor deposits compare with lymph node metastases in prognostic significance. This study evaluated the survival impact of tumor deposits relative to lymph node metastases in stage III colon cancer. The US National Cancer Database (2010-2012) was reviewed for resectable stage III adenocarcinoma of the colon, and stratified by presence of tumor deposits and lymph node metastases. Univariate and multivariate survival analyses were performed. Of 6424, 10.1% had both tumor deposits and lymph node metastases [5-year survival (5YS) 40.2%], 2.5% had tumor deposits alone (5YS 68.1%), and 87.4% had lymph node metastases alone (5YS 55.4%). Patients with lymph node metastases alone tended to have a greater number of lymph nodes retrieved (20.9 versus 18.8, p = 0.0126) and were more likely to receive adjuvant therapy (66.9 vs 58.0%, p = 0.003) than those with only tumor deposits. Patients with both had significantly worse survival at all T stages (p < 0.05, all). There was no significant difference in survival between tumor deposits alone and lymph node metastases alone at any T stage (p > 0.8, all). After controlling for patient, disease, and treatment characteristics, patients with tumor deposits alone [hazard ratio (HR) 0.56, p = 0.001] or only lymph node metastases (HR 0.64, p < 0.001) were associated with improved survival relative to patients with both. Concomitant presence of tumor deposits and lymph node invasion carries poor prognostic significance. Tumor deposits alone appear to have prognostic implications similar to lymph node invasion alone.