Radiation therapy in the management of rectal cancer.

For many years, rectal carcinoma has been treated by surgery alone. However, survival rates have not improved historically and local recurrence remains a problem. Adjuvant radiation therapy does have a role in this disease. While the optimal scheduling and dose are not determined yet, it can certainly prevent local recurrence and potentially increase survival. There are advantages to delivering radiation therapy preoperatively and postoperatively and the combination of low-dose preoperative radiation therapy and postoperative radiation therapy in selected patients ("sandwich" therapy) appears promising. The use of chemotherapy in combination with radiation therapy may further improve survival rates. Care must be taken in patients treated with rectal carcinoma to minimize the normal tissue irradiated to decrease complications and deliver tumoricidal doses to the areas at risk. Techniques are available to both the surgeon and the radiation oncologist to minimize the amount of small bowel irradiated. Radiation therapy also has a role in the treatment of very early rectal cancers as part of a sphincter-saving procedure and in the treatment of advanced or recurrent rectal cancers. In the latter, intraoperative radiation therapy plays an important role in controlling recurrent or residual rectal cancer.