Prognosis and Risk Factors in Patients With Non-radical Circumferential Resection Margin After Rectal Cancer Surgery

BACKGROUND/AIM: Circumferential resection margin (CRM) has been shown to be a strong predictor of risk of local recurrence (LR) and distant metastases (DM) in patients with rectal cancer treated with total mesorectal excision (TME). However, not all patients with a CRM of zero develop LR or DM. This study aimed to identify factors associated with disease-free survival (DFS) despite non-radical excision (CRM=0 mm). PATIENTS AND METHODS: Patients surgically treated for adenocarcinoma of the rectum between 2005 and 2013 were identified through the Swedish ColoRectal Cancer Registry. RESULTS: Of 8,392 patients included in the study, 159 (1.8%) were found to have CRM 0 mm. The rates of LR (n=27; 17%) and DM (n=62; 39%) were high in the CRM 0 mm group; however, more than half of these patients developed neither (n=84; 52.8%). Stage II disease was associated with a higher DFS [odds ratio (OR)=2.15; 95% confidence interval (CI)=1.11-4.18] compared with stage III disease. Neoadjuvant chemotherapy was a negative prognostic factor of DFS (OR=0.47, 95% CI=0.23-0.97) independent of the stage of disease. CONCLUSION: Over half of the patients with CRM 0 mm after rectal cancer surgery did not develop LR or DM. Lower stage of disease and no neoadjuvant chemotherapy were associated with a better DFS. These findings suggest that other biological or molecular factors may influence prognosis after non-radical excision, highlighting the need for further research to improve postoperative management and follow-up.