Preoperative chemotherapy and pelvic radiation for tethered or fixed rectal cancer: a phase II dose escalation study.

Abstract

To study the impact of preoperative radiation dose escalation and postoperative adjuvant chemotherapy on the outcome of tethered and fixed rectal carcinoma. We have treated 156 patients with 3 consecutive preoperative chemoradiation protocols with escalating treatment intensity. Schedule 1 consisted of 40 Gy radiation with concurrent 5-fluorouracil (5-FU) infusion and mitomycin C. Schedule 2 used a sandwich design with preoperative (40 Gy) and postoperative (18 Gy) radiation with concomitant 5-FU infusion, leucovorin, and mitomycin C. In schedule 3, the preoperative radiation dose was increased to 50 Gy and adjuvant 5-FU/leucovorin chemotherapy was added following surgery. There were 54, 27, and 75 patients treated in schedules 1, 2, and 3, respectively. The resectability was 91% for schedule 1 and 100% for both schedules 2 and 3. A dose-response relationship was observed between the radiation dose and the tumor downstaging and local control. The pathological complete response (T0N0M0) rates for schedules 1, 2, and 3 were 4%, 15%, and 25%, respectively. The respective rates of tumor downstaging were 41%, 33%, and 68%, respectively. The 5-year local relapse-free rates were 67% for schedule 1 (40 Gy), 96% for schedule 2 (58 Gy), and 92% for schedule 3 (50 Gy) (p = 0.0011). The addition of postoperative chemotherapy appeared to improve both the survival and the relapse-free survival. The 5-year survival was increased from 52% to 84% (p = 0.0004) and the 5-year progression-free survival was improved from 48% to 74% (p = 0.0008). Preoperative 5-FU infusion, leucovorin, mitomycin C, and 50-Gy pelvic radiation, followed by postoperative bolus 5-FU/leucovorin chemotherapy, appeared to be an effective treatment for tethered/fixed rectal cancers. However, its therapeutic efficacy could only be validated in randomized studies.