Purpose To investigate oxaliplatin combined with fluorouracil-based chemoradiotherapy as preoperative treatment for locally advanced rectal cancer. Patients and Methods Seven hundred forty-seven patients with resectable, locally advanced (cT3-4 and/or cN1-2) adenocarcinoma of the mid-low rectum were randomly assigned to receive pelvic radiation (50.4 Gy in 28 daily fractions) and concomitant infused fluorouracil (225 mg/m2/d) either alone (arm A, n = 379) or combined with oxaliplatin (60 mg/m2 weekly × 6; arm B, n = 368). Overall survival is the primary end point. A protocol-planned analysis of response to preoperative treatment is reported here. Results Grade 3 to 4 adverse events during preoperative treatment were more frequent with oxaliplatin plus fluorouracil and radiation than with radiation and fluorouracil alone (24% v 8% of treated patients; P < .001). In arm B, 83% of the patients treated with oxaliplatin had five or more weekly administrations. Ninety-one percent, compared with 97% in the control arm, received ≥ 45 Gy (P < .001). Ninety-six percent versus 95% of patients underwent surgery with similar rates of abdominoperineal resections (20% v 18%, arm A v arm B). The rate of pathologic complete responses was 16% in both arms (odds ratio = 0.98; 95% CI, 0.66 to 1.44; P = .904). Twenty-six percent versus 29% of patients had pathologically positive lymph nodes (arm A v arm B; P = .447), 46% versus 44% had tumor infiltration beyond the muscularis propria (P = .701), and 7% versus 4% had positive circumferential resection margins (P = .239). Intra-abdominal metastases were found at surgery in 2.9% versus 0.5% of patients (arm A v arm B; P = .014). Conclusion Adding oxaliplatin to fluorouracil-based preoperative chemoradiotherapy significantly increases toxicity without affecting primary tumor response. Longer follow-up is needed to assess the impact on efficacy end points.
The Impact of Surgical Timing on Pathologic Tumor Response after Short Course and Long Course Preoperative Chemoradiation for Locally Advanced Rectal Adenocarcinoma
