Objective: The Swedish Rectal Cancer Trial (SRCT) demonstrated that a short-term regimen of high-dose preoperative radiotherapy (5 x 5 Gy) not only reduced the local recurrence rates but also improved the overall survival rate. This compelling evidence will have a significant impact on the primary treatment of rectal cancer. The authors' aim was to explore the representativeness of the study.

Summary background data: Until the SRCT was presented in 1997, no major trial had established that radiotherapy has a positive effect on the overall survival rate.

Methods: A review of all rectal cancer cases reported to the Swedish Cancer Registry during the same period that the SRCT accrued patients (1987 to 1990) was performed at 57 of 68 participating hospitals. At these 57 hospitals, there were 2366 patients with invasive rectal cancer, with 1664 of these patients fulfilling the criteria for inclusion in the SRCT.

Results: Fifty-two percent (866/1664) of eligible patients were included in the SRCT. The patients not included, of whom 8% (67/798) received adjuvant radiotherapy, had an overall 5-year survival rate of 48%, which was identical to the overall survival rate in the SRCT surgery-alone group (48%) but was inferior to the SRCT radiotherapy group (58%). The cancer-specific 5-year survival rates were 65% and 66% among the patients not included and the surgery-alone group, respectively. The local recurrence rates reached 27% in both groups. The results were still comparable when stratifying for curative surgery, tumor stage, and surgical procedure.

Conclusions: The achieved inclusion level of 52% in a randomized multicenter trial is comparatively high. Because the population in the SRCT was representative, it was concluded that the study results are reliable.