Postoperative radiation therapy for rectal cancer. An interim analysis of a prospective, randomized multicenter trial in The Netherlands. The authors assessed the potential benefit of postoperative radiation therapy for rectal cancer in a two-arm, prospective multicenter trial. One hundred seventy-two patients who had undergone surgical resection for rectal adenocarcinoma were randomly assigned to either treatment consisting of external irradiation to a dose of 5000 cGy in 5 weeks or a control group (no adjuvant therapy). It was assumed that the number of cells remaining after radical surgery would be low and that the dose of 5000 cGy would be adequate in eradicating the majority of those cells. The number of local recurrences was lower in the treated group of patients, but the difference was not statistically significant. It was assumed that if a significant reduction in the number of local recurrences could be obtained, improved (disease-free) survival would result. No influence on disease-free or overall survival could be detected. These results were in agreement with those reported in Europe and the US, and it was concluded that postoperative radiation therapy alone cannot be justified as a routine procedure in the primary management of resectable rectal cancer. 