Impact of Preoperative Chemo-radiation Therapy on Systemic Failure in LocallyAdvanced Rectal Cancer

Background and objectives: Advanced rectal cancers require local and systemic control. Chemo radiotherapy (CRT) is adequate to achieve adequate local control. Systemic control, however, is a dominant obstacle remained in debates. We compared oncology outcome in both arms in patients with advanced rectal cancers in order to identify high-risk group of distant metastasis. Methods: Data for 723 patients for advanced rectal cancer from 2005 to 2013 retrieved retrospectively. Patients were classified to CRT (n=364) or no CRT (n=359) arms. Results: CRT group showed greater local control and achieved pT stage 0, 1, or 2 in 43.7% vs. 28.4% in no CRT (p<0.001) and less CEA marker (11.17 ± 25.2 vs. 6.14 ± 11.3, p<0.001), respectively. Although CRT group had higher rates of advanced tumors, cT3 or T4 (341(93.7%) vs. 294(81.9%), p<0.001) and CRM threat (167 (45.9%) vs. 30(8.4%); p<0.001). Overall local recurrence rate observed in no CRT 3% compared to 2.1% in CRT arm, (p<0.005). Systemic recurrence rate was similar in both groups, (22.5% vs. 23%), respectively. Conclusion: CRT is efficient to downstage locally advanced rectal cancer, not systemic control though. Early recognition of high-risk group is recommended in order to consider CRT modification ahead of planned surgery.