Adjuvant treatment for rectal cancer: current status.

Surgery is still the cornerstone of curative treatment for rectal cancer. A combination of postoperative radiation and chemotherapy is the preferred adjuvant treatment for TNM stages II and III rectal cancer. Although studies combining 5-fluorouracil (5-FU) and the investigational agent semustine (methyl-CCNU) with radiation showed some survival benefit, preliminary results of recent studies suggest that radiation with 5-FU alone is an effective substitute. Preoperative radiation treatment has several advantages over postoperative radiotherapy. The major disadvantage, that tumors may be downstaged, preventing exact evaluation of treatment results, may be overcome by using rectal ultrasound for preoperative staging. Another promising treatment is preoperative radiation combined with 5-FU as a radiosensitizer and for possible increased systemic effect. Studies are needed to find a better, less toxic radiosensitizer, to explore new chemotherapy combinations with 5-FU (such as levamisole), and to define the proper dose sequence and integration.