Abstract. Preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer not only improves the postoperative local control rate, but also induces downstaging. However, it has not been established how to individually select patients who receive effective preoperative CRT. The aim of this study was to identify a predictor of response to preoperative CRT for locally advanced rectal cancer. This study is additional to our multicenter phase II study evaluating the safety and efficacy of preoperative CRT using oral fluorouracil (UMIN ID: 03396). From April, 2009 to August, 2011, 26 biopsy specimens obtained prior to CRT were analyzed by cyclopedic microarray analysis. Response to CRT was evaluated according to a histological grading system using surgically resected specimens. To decide on the number of genes for dividing into responder and non-responder groups, we statistically analyzed the data using a dimension reduction method, a principle component analysis. Of the 26 cases, 11 were responders and 15 non-responders. No significant difference was found in clinical background data between the two groups. We determined that the optimal number of genes for the prediction of response was 80 of 40,000 and the functions of these genes were analyzed. When comparing non-responders with responders, genes expressed at a high level functioned in alternative splicing, whereas those expressed at a low level functioned in the septin complex. Thus, an 80-gene expression set that predicts response to preoperative CRT for locally advanced rectal cancer was identified using a novel statistical method.
720 Background: Fluorouracil-based chemoradiotherapy (CRT) is regarded as a standard perioperative treatment in locally advanced rectal cancer. We investigated the efficacy and safety of substituting fluorouracil with the oral prodrug S-1. Methods: A multi-institutional (17 specialized centers), interventional phase II trial, was conducted from April 2009 to August 2011. For inclusion, patients must fulfill the following requirements before neoadjuvant CRT: (i) histologically proven rectal carcinoma; (ii) tumor located in the rectum (upper, lower); (iii) cancer classified as T3-4, N0–3 and M0; Two cycles of neoadjuvant CRT with S-1 (100 mg/m2 on days 1-5, 8-12, 22-26, and 29-33) was administered, and irradiation (total 45Gy/25fr, 1.8Gy/day, on days 1-5, 8-12, 15-19, 22-26, and 29-33) was performed. Total mesorectal excision was performed during the 4th and 8th week after the end of the neoadjuvant CRT. The primary endpoint is rate of complete treatment of neoadjuvant CRT. Secondary endpoints are response rate of neoadjuvant CRT, short-term clinical outcomes, rate of curative resection, and pathological response (grade2/3). Results: This trial included 37 patients (clinical StageIIA: 8, IIIB: 19, IIIC: 10; tumor located in the upper rectum; 4, the lower rectum; 33). A complete treatment of neoadjuvant CRT was found in 86.5% of patients (95%CI;75.5-97.5%), and an adverse event (grade 3/4) occurred in 4 patients(11.1%). Response rate (PR/CR;RECIST 1.0) was 56.8% (95%CI; 40.8-72.7%), and pathologic response rate (grade2/3) was 48.6% (95%CI; 32.5-64.8%). The median operating time was 448.5 min (IQR 340.5-505.5), and median blood loss was 422.5 mL (IQR 182.5-1125). Grade 3-4 postoperative complications occurred in 6 (16.7%) patients. The most common grade 3 or 4 postoperative complication was anastomotic leakage (2 [5.6%]). The 3-year overall survival rate was 88.5%. The 3-year disease free survival rate was 70.9%. Median length of follow-up was 42 months. Conclusions: A neoadjuvant-synchronus S-1+Radiotherapy for locally advanced rectal cancer is feasible in terms of pathological response, adverse events, accompany with favorable long-term outcome. Clinical trial information: 03396.
793 Background: We have reported the effectiveness of neoadjuvant radiotherapy (RT) combined with S-1 in terms of compliance and pathologic response for locally advanced rectal cancer. In the present study, we aimed to evaluate the safety and efficacy of laparoscopic surgery for locally advanced rectal cancer following neoadjuvant RT combined with S-1 in comparison with open surgery. Methods: Two multicenter prospective phase II trials were conducted (UMIN003396, UMIN003398). A total of 63 patients with locally advanced rectal cancer classified as T3-4, N0-3, and M0 were enrolled, and neoadjuvant RT combined with S-1 and total mesorectal excision with D3 lymphadenectomy was performed. Of these, 57 patients were analyzed and divided into a laparoscopic group (LAP, n = 43) and open group (OP, n = 14). We evaluated the short- and long-term outcomes of laparoscopic surgery compared with open surgery by univariate and multivariate analyses. Results: In the patient background, there were no significant differences between the two groups except that cases with T3 and N0 were significantly higher in the LAP compared with the OP. In the operative findings, operation time was longer (mean 447 min vs. 352 min, p = 0.007) and blood loss was lesser (median 220 ml vs. 485 ml, p = 0.033) in the LAP than those in the OP. Although there were no significant differences observed in the incidence of perioperative and late complications between the two groups, reoperation within 30 days was significantly less in the LAP compared with the OP (1 case vs. 5 cases, p = 0.0004). In the multivariate analysis, a distance of the tumor from anal verge within 3 cm was the independent risk factor for reoperation within 30 days. Furthermore, estimated 5-year disease-free survival (LAP 72 % vs. OP 73 %, p = 0.945) and 5-year overall survival (LAP 76 % vs. 75 %, p = 0.836) didn’t significantly differ between the two groups in the Kaplan–Meier curve. Conclusions: The findings of this study demonstrated that laparoscopic surgery for locally advanced rectal cancer following neoadjuvant RT combined with S-1 could be an optional procedure in terms of short- and long-term outcomes. Clinical trial information: UMIN000003396, UMIN000003398.
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