Symposium on rectal cancer: 3. The case for adjuvant radiotherapy for rectal cancer

Adjuvant radiotherapy for rectal cancer is intended to eradicate subclinical deposits of cancer cells not removed at surgery. These residual cells are found most commonly at the resection margin of the primary tumour and in transected cancer-bearing lymphatics or vessels. Refinements in surgical technique have been associated with a reduction in the risk of pelvic recurrence in some nonrandomized series. However, clinical trials have shown that the combinations of radiotherapy and chemotherapy, and in some instances radiotherapy alone, reduce the risk of recurrence and may improve survival rates compared with those of surgery alone. It is premature to consider that adjuvant pelvic radiotherapy is unnecessary.