Low-dose preoperative radiation postpones recurrences in operable rectal cancer: results of a randomized multicenter trial in Western Norway

In Norway, only about 40 percent of patients with operable rectal cancers survive five years after surgery. Among the patients who relapse after surgery, from 30 to 60 percent experience recurrence of tumor in the locoregional area only, with no metastatic disease. These patients represent a population of patients who may well be cured if improvements in surgical treatment can be achieved. One method to improve the success of potentially curative surgery for rectal cancer that is under investigation is preoperative radiation. Several preliminary trials have suggested that preoperative radiation may provide some survival benefit for these patients. To objectively evaluate the benefits of preoperative radiotherapy, a controlled study was designed to examine survival of patients with operable rectal cancer with or without preoperative radiation. A total of 145 patients received surgical treatment only, and 155 patients received preoperative radiation consisting of a dose of 3,150 cGy in 18 fractions two to three weeks prior to surgery. (A Gy, or Gary, is 1 joule of energy absorbed per kilogram of tissue.) Overall, the five-year survival of the patients was 57.5 percent and 56.7 percent for the control and the radiation groups. For those patients for whom the surgery was regarded as possibly curative, the five-year survival rates were 60.9 percent in the control group and 64.2 percent in the group receiving radiation therapy.These differences were not statistically significant. It was observed that while the proportion of patients in relapse was the same in both groups, the duration of the response prior to relapse was not the same. Patients in the control group relapsed after an average of 13.3 months, while patients treated with preoperative radiation enjoyed remissions lasting an average of 27.1 months. It should be mentioned that the rectum is relatively resistant to the harmful effects of radiation, and a dose of 3,150 cGy is significantly less than the area is capable of tolerating. Considering the extension of remission as a result of the preoperative radiation, it is plausible that higher radiation doses, perhaps around 5,600 cGy, may provide improved long-term survival. (Consumer Summary produced by Reliance Medical Information, Inc.)