97P - The role of adjuvant chemotherapy according to the status of surgical margin in rectal cancer

Abstract

BackgroundAdjuvant chemotherapy has been recommended for patients who have locally advanced rectal cancer. However, the role of adjuvant chemotherapy in patients with positive surgical margin has not been clarified. We investigated the benefit of adjuvant chemotherapy according to the surgical margin in locally advanced rectal cancer. MethodsA total of 1801 rectal cancer patients staging cT3-4N0-2M0 were included. The patients were eligible when tumors were pathologically confirmed adenocarcinoma, located within 10cm from anal verge, and staged cT3-4N0-2M0. Before surgery, all patients received radiation therapy at a dose of 50.4 Gy in 28 fractions with concurrent 5-fluorouracil or capecitabine. Curative surgery including TME was performed 4 to 8 weeks after radiotherapy. Adjuvant chemotherapy was performed after 4-6 weeks after surgery. ResultsAdjuvant chemotherapy was given to 1531 patients (85.0%). Patients with positive circumferential resection margin or distal resection margin were 205 (11.4%). With patients with positive surgical margin (n = 205), the 5-year recurrence-free survival (RFS) showed a significant difference between adjuvant chemotherapy group and no adjuvant chemotherapy group (50.3% vs. 30.9%, p = 0.01). The 5-year overall survival rate was 72.6% in adjuvant chemotherapy group and 57.2% in no adjuvant chemotherapy group (p = 0.09). With patients with the negative margin (n = 1596), the 5-year RFS rate did not show any difference between two groups (75.6% vs. 76.8%, p = 0.94). On multivariate analysis, adjuvant chemotherapy was significantly associated with RFS in patients who had the positive surgical margin (Hazard ratio (HR): 0.48, 95% confidence interval (CI): 0.25-0.94, p = 0.032). In contrast, there was no significant association between adjuvant chemotherapy and RFS in those with negative surgical margin (HR: 0.99, 95% CI: 0.72-1.35, p = 0.94). ConclusionsPatients who received adjuvant chemotherapy showed a significantly improved 5-year RFS rate compared with those who did not receive adjuvant chemotherapy if the patients had positive surgical margin. The benefit of adjuvant chemotherapy was more remarkable in patients with positive surgical margin compared to those with negative surgical margin. Legal entity responsible for the studyThe author. FundingHas not received any funding. DisclosureThe author has declared no conflicts of interest.