Abstract
BACKGROUND: The present study aimed to investigate the cause-specific survival (CSS) of very small rectal cancer in the context of preoperative serum carcinoembryonic antigen (CEA) elevation. METHODS: Patients diagnosed with node-negative rectal cancer from the Surveillance, Epidemiology, and End Results (SEER) database from January 2004 to December 2010 meeting the inclusion criteria were identified for this study. The Cox proportional hazards regression analyses were conducted to identify independent factors associated with CSS. Pearson's chi-squared tests and Kaplan-Meier methods were performed. RESULTS: A total of 8,413 patients were included into our study. Kaplan-Meier analyses showed lower 7-year CSS rate of very small tumors (≤5 mm) compared to those larger than 40 mm (70.4% vs. 76.0%, log-rank P=0.469). Multivariate Cox analyses showed that patients with very small tumor size (≤5 mm) was also associated with a significantly increased risk of cancer-specific mortality compared with those with large tumor size (HR =2.567, 95% CI: 1.285 to 5.130, P=0.008, using ≥41 mm, C+ as a reference). CONCLUSIONS: Very small tumor size in the context of preoperative serum CEA elevation could be a surrogate for biological aggressiveness. Our finding would provide a better understanding of tumor biology for us and elicit more future biological researches.