Rectal cancer level significantly affects rates and patterns of distant metastases among rectal cancer patients post curative-intent surgery without neoadjuvant therapy

BACKGROUND Rectal cancer patients have a higher incidence of pulmonary metastases than those with colon cancer. This study aimed to examine the effects of rectal cancer level on recurrence patterns in rectal cancer patients. METHODS Patients with T3/T4 rectal cancers who underwent surgery between 2002 and 2006 were recruited in this study. All the patients were followed up on until death. Recurrence patterns and survival rates were calculated in relation to clinical variables. RESULTS There were 884 patients were enrolled in this study. Patients with low-rectal cancer had significantly worse five-year overall survival (OS) and disease-free survival (DFS) rates (47.25% and 44.07%, respectively) than patients with mid-rectal (63.46% and 60.22%, respectively) and upper-rectal cancers (73.91% and 71.87%, respectively). The level of the tumor (P <0.001), nodal status (P <0.001), tumor invasion depth (P <0.001), and tumor differentiation (P = 0.047, P = 0.015) significantly affected the surgical outcomes related to OS and DFS in the univariate and multivariate analyses. Furthermore, the level of the rectal cancer was a significant risk factor (hazard ratio 1.114; 95% CI, 1.074 to 1.161; P <0.001) for local recurrence, lung metastases, bone metastases, and systemic lymph node metastases. Significantly higher incidence rates of bone (53.8%) and brain metastases (22.6%) after initial lung metastases rather than initial liver metastases (14.8% and 2.9%, respectively) were also observed. CONCLUSIONS For rectal cancer patients who underwent surgical resection, the rectal cancer level significantly affected surgical outcomes including rates and patterns of distant metastases.