541P - Upfront radical surgery with total mesorectal excision (TME) versus preoperative chemoradiotherapy followed by TME in clinical stage II/III patients with rectal cancer: A propensity score analysis

Abstract

BackgroundAlthough the current standard preoperative chemoradiotherapy (PCRT) for stage II/III rectal cancer decreases the risk of local recurrence, it does not improve overall survival and increase the likelihood of preoperative overtreatment, especially in patients without the circumferential resection margin (CRM) involvement. MethodsStage II/III rectal cancer without CRM involvement and lateral lymph node metastasis was radiologically defined by preoperative magnetic resonance imaging (MRI). Patients who received either PCRT followed by TME (PCRT group) or upfront surgery with TME (US group) between 2011 and 2016 were analyzed. We derived cohorts of PCRT group versus US group using propensity-score matching using staging, age, and distance from anal verge). Three-year relapse-free survival rate, disease-free survival (DFS), and overall survival (OS) were compared between two groups. ResultsA total of 221 patients were analyzed after propensity score matching. There were no differences in baseline characteristics. The median follow-up was 75 months (range, 28-101). No difference in 3-year relapse-free survival rate was noted between PCRT and US groups (89% vs 92% with US; P=0.657). Likewise, there was no statistically significant difference in DFS (7.7 years vs 8.0 years with US; P=0.162) and OS (8.1 years vs 8.3 years with US; P=0.431), respectively. The rates of locoregional recurrence (2.9% vs 0% with US, P=0.301) and distant metastasis (7.4% vs 7.1%, P=1.0) at 3-years were not significantly different between two groups. Interestingly, approximately half of patients had pathologic stage I cancer in both groups (56% with PCRT vs 45% with US; P=0.167) and 69% of patients in US group had not received adjuvant treatment, suggesting that upfront surgery without neoadjuvant therapy can be considered in early stage patients with good prognosis. ConclusionsPCRT may not be required for all stage II/III rectal cancer patients, especially for the MRI-based intermediate-risk group (cT1-2/N1, cT3N0) without CRM involvement and lateral lymph node metastasis. Further prospective studies are warranted. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.