Postoperative radiochemotherapy in rectal cancer comparison of two combination schemes: alternating versus concomitant.

Aims and background: To compare the results on disease control and toxicity of two different schedules of adjuvant combined treatment in advanced rectal cancer. Methods: From January 1995 to September 1998, 127 patients with stage B2-C rectal cancer were treated with postoperative chemotherapy and radiotherapy with two different schemes: three cycles of 5-fluorouracil and leucovorin followed by pelvic radiotherapy and three weeks after radiation therapy was completed, another three cycles of chemotherapy were administered (alternating arm), or two cycles of 5-fluorouracil and leucovorin followed by concurrent radiochemotherapy and three weeks after ending another two cycles of 5-fluorouracil and leucovorin were administered (concomitant arm). Results: Grade 3 acute toxicity was more frequent in the concomitant schedule group (33% vs 13%, P = 0.014). In the alternating schedule group, the acute adverse effects were observed after an average radiation dose of 28.4 Gy and in the concomitant schedule group after an average dose of 22.7 Gy (P = 0.012). In the arm of concomitant treatment, 37.8% of patients had to interrupt the irradiation for severe toxicity compared to 10.4% in the arm of alternating treatment (P = 0.001). There was no difference in the rate of late toxicity. The actuarial overall survival rates at 3 and 5 years were, respectively, 68.8% and 56.6% in the alternating arm and 75.5% and 61.8% in the concomitant arm (P = 0.4599). There were no differences between the two arms in the 5-year actuarial rates of overall recurrence (47% vs 51.3%, P = 0.722), local recurrence (34.6% vs 35.7%, P = 0.935) or distant recurrence (32.7% vs 31.8%, P = 0.983). Conclusions: For patients with B2-C rectal cancer, postoperative treatment with an alternating scheme of chemoradiotherapy is as effective as a concomitant scheme in control of the disease. The concomitant scheme had a higher incidence, earlier appearance and higher severity of intestinal acute toxicity than the alternating scheme, with a lower completion rate of chemoradio-therapy but without any influence on late toxicity incidence.