ArticlesAdjuvant radiotherapy for rectal cancer: a systematic overview of 8507 patients from 22 randomised trials*
Introduction
Despite apparently curative surgery, rectal cancer recurs locally in up to 25% of patients. Radiotherapy might reduce risk of local recurrence and improve survival rates. At least 28 randomised trials have compared patients with rectal cancer who had adjuvant preoperative or postoperative radiotherapy with those who had surgery alone. We have done an overview (meta-analysis) of their findings to give a more accurate and balanced account. Because a larger number of patients is analysed in a systematic overview, random errors are smaller than in individual trials. Additionally, a review of all related trials avoids potentially misleading selective emphasis on more (or less) promising results, which can arise solely by chance, especially since not all results are published, and those that are tend to have more striking results.
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Trials
We identified trials and checked data according to the procedures described by the Early Breast Cancer Trialists' Collaborative Group.1 We included trials if they were unconfounded, correctly randomised comparisons between either preoperative or postoperative radiotherapy and no radiotherapy for rectal cancer, and had started before Jan 1, 1987. Trials of radiotherapy for colon cancer were not eligible. To be correctly randomised, trials had to have used treatment allocation methods that
Overall survival
Overall survival was only marginally better in patients allocated radiotherapy than those allocated none (figure 2), with 45·0 versus 42·1% alive at 5 years, and 26·9% vs 25·3% alive at 10 years. Overall, the yearly death rate was 5·4% (SE 2·9, 95% CI 0–11%) lower in patients who had radiotherapy than in those who had none (figure 1); the reductions did not differ significantly between patients who had preoperative radiotherapy and those who had postoperative radiotherapy (5·6%, SE 3·3; and
Discussion
In this systematic review of data from 8507 patients in 22 trials of adjuvant radiotherapy for rectal cancer, radiotherapy both before and after surgery substantially reduced the risk of local recurrence in apparently curatively resected patients and moderately reduced deaths from rectal cancer. The largest reductions were in studies of preoperative radiotherapy with biologically effective doses of 30 Gy or more; no significant reductions were recorded in studies of radiotherapy schedules with
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