Adjuvant versus neoadjuvant radiochemotherapy for locally advanced rectal cancer. A progress report of a phase-III randomized trial (protocol CAO/ARO/AIO-94).

Aim: The standard treatment for patients with clinically resectable rectal cancer is surgery. Postoperative radiochemotherapy is recommended for patients with advanced disease (pT3/4 or pN+). In recent years, encouraging results of preoperative radiotherapy have been reported. This prospective randomized phase-III trial (CAO/ARO/AIO-94) compares the efficacy of neoadjuvant radiochemotherapy to standard postoperative radiochemotherapy. We report on the design of the study and first results with regard to toxicity of radiochemotherapy and postoperative morbidity.

Patients And Methods: Patients with locally advanced operable rectal cancer (uT3/4 or uN+, Mason CS III/IV) were randomly assigned to pre- or postoperative radiochemotherapy: A total dose of 50.4 Gy (single dose 1.8 Gy) was applied to the tumor and the pelvic lymph nodes. 5-FU (1,000 mg/m2/d) was administered concomitantly in the first and fifth week of radiation as 120-h continuous infusion. Four additional cycles of 5-FU chemotherapy (500 mg/m2/d, i.v. bolus) were applied. Radiochemotherapy was identical in both arms except for a small-volume boost of 5.4 Gy in the postoperative setting. Time interval between radiochemotherapy and surgery was 4-6 weeks in both arms. Techniques of surgery were standardized and included total mesorectal excision. In addition, stratification according to surgeons involved has been provided for. Primary endpoints of the study are 5-year overall-survival, local and distant control, secondary endpoints include rate of curative (R0) resections and sphincter saving procedures, toxicity of radiochemotherapy, surgical complications and quality of life.

Results: As of 15th November 2000, 628 patients were randomized from 26 participating institutions: 310 patients were randomized to postoperative radiochemotherapy, 318 patients to preoperative radiochemotherapy. Acute toxicity (WHO) of radiochemotherapy was low, with less than 15% of patients experiencing Grade 3 or higher toxicity: The principal toxicity was diarrhea, with 12% in the postoperative radiochemotherapy arm and 10% in the preoperative radiochemotherapy arm having Grade-3, and 1% in either arm having Grade-4 diarrhea. Erythema, nausea and leukopenia were the next common toxicities, with less than 3% of patients in either arm suffering Grade 3 or greater leukopenia or nausea. Postoperative complication rates were similar in both arms, with 12% (postoperative radiochemotherapy) and 13% (preoperative radiochemotherapy) of patients, respectively, suffering from anastomotic leakage, 4% (postoperative radiochemotherapy) and 3% (preoperative radiochemotherapy) from postoperative bleeding, and 6% (postoperative radiochemotherapy) and 5% (preoperative radiochemotherapy) from delayed wound healing.

Conclusion: The patient accrual of our trial is satisfactory, neoadjuvant radiochemotherapy is well tolerated and bears no higher risk for postoperative morbidity.