THE RATIONALE TO SWITCH FROM POSTOPERATIVE HYPERFRACTIONATED ACCELERATED RADIOTHERAPY TO PREOPERATIVE HYPERFRACTIONATED ACCELERATED RADIOTHERAPY IN RECTAL-CANCER

Purpose: To demonstrate the feasibility of preoperative Hyperfractiona ted Accelerated RadioTherapy (preop-HART) in rectal cancer and to expl ain the rationales to switch from postoperative HART to preoperative H ART. Methods and Materials: Fifty-two consecutive patients were introd uced in successive Phase I trials since 1989. In trial 89-01, postoper ative HART (48 Gy in 3 weeks) was applied in 20 patients, In nine pati ents with locally advanced rectal cancer, considered unresectable by t he surgeon, 32 Gy in 2 weeks was applied prior to surgery (trial 89-02 ), Since 1991, 41.6 Gy in 2.5 weeks has been applied preoperatively to 23 patients with T3-T4 any N rectal cancer immediately followed by su rgery (trial 91-01), All patients were irradiated at the department of radiation-oncology with a four-field box technique (1.6 Gy twice a da y and with at least a 6-h interval between fractions), The minimal acc elerating potential was 6 MV, Acute toxicity was scored according to t he World Health Organization (WHO for skin and small bowel) and the Ra diation Therapy Oncology Group criteria (RTOG for bladder), This was d one weekly during treatment and every 3 months thereafter, Small bowel volume was estimated by a modified ''Gallagher's'' method. Results: A cute toxicity was acceptable both in postoperative and preoperative se tup, The mean acute toxicity was significantly lower in trial 91-01 co mpared to 89-01, This difference was due to the smaller amount of smal l bowel in irradiation field and lower total dose in trial 91-01, More over, there was a significantly reduced delay between surgery and radi otherapy favoring trial 91-01 (median delay 4 days compared to 46 days in trial 89-01), Nearly all patients in trial 89-02 and 91-01 underwe nt surgery (31 out of 32; 97%), Resection margins were negative in 29 out of 32, Hospitalization duration in trial 91-01 was not significant ly different from trial 89-01 (19 vs, 21 days, respectively). Conclusi ons: Hyperfractionated accelerated radiotherapy immediately followed b y surgery is feasible as far as acute toxicity is concerned, Preoperat ive HART is favored by a significantly lower acute toxicity related, i n part, to a smaller amount of irradiated small bowel, and a shorter d uration of the delay between radiotherapy and surgery, Moreover, the h ospital stay after preoperative HART is not significantly increased.