A phase II trial of neoadjuvant chemoradiation and local excision for T2N0 rectal cancer: Preliminary results of the ACOSOG Z6041 trial

Purpose: We designed American College of Surgeons Oncology Group (ACOSOG) Z6041, a prospective, multicenter, single-arm, phase II trial to assess the efficacy and safety of neoadjuvant chemoradiation (CRT) and local excision (LE) for T2N0 rectal cancer. Here, we report tumor response, CRT-related toxicity, and perioperative complications (PCs). Methods: Clinically staged T2N0 rectal cancer patients were treated with capecitabine and oxaliplatin during radiation followed by LE. Because of toxicity, capecitabine and radiation doses were reduced. LE was performed 6 weeks after CRT. Patients were evaluated for clinical and pathologic response. CRT-related complications and PCs were recorded. Results: Ninety patients were accrued; 6 received nonprotocol treatment. The remaining 84 were 65% male; median age 63 years; 83% Eastern Cooperative Oncology Group performance score 0; 92% white; mean tumor size 2.9 cm; and average distance from anal verge 5.1 cm. Five patients were considered ineligible. Therapy was completed per protocol in 79 patients, but two patients did not undergo LE. Among 77 eligible patients who underwent LE, 34 patients achieved a pathologic complete response (44%) and 49 (64%) tumors were downstaged (ypT0-1), but 4 patients (5%) had ypT3 tumors. Five LE specimens contained lymph nodes; one T3 tumor had a positive node. All but one patient had negative margins. Thirty-three (39%) of 84 patients developed CRT-related grade ≥3 complications. Rectal pain was the most common PC. Conclusions: CRT before LE for T2N0 tumors results in a high pathologic complete response rate and negative resection margins. However, complications during CRT and after LE are high. The true efficacy of this approach will ultimately be assessed by the long-term oncologic outcomes.