PURPOSE:We retrospectively analyzed prognostic factors for surgical resection and intraoperative radiation therapy to identify indicators for this treatment strategy.METHODS:Thirty‐nine consecutive patients with locally recurrent colorectal cancer who underwent surgical resection with intraoperative radiation therapy from January 1, 1987, to June 30, 1999, were analyzed. The mean electron energy was 10.5 MeV and the mean intraoperative radiation dose was 22.6 Gy. Kaplan‐Meier survival estimates were obtained for the 37 patients who recovered postoperatively. Prognostic factors were analyzed univariately by log‐rank test and multivariately by Cox's proportional hazards model.RESULTS:Three‐year cumulative survival was 44 percent (standard error = 11) for 26 patients free of unresectable distant metastasis who underwent surgical resection and intraoperative radiation therapy for pelvic recurrence of colorectal cancer, but none of the 11 patients with unresectable distant metastasis survived 3 years. Preoperative prognostic factors which were significant on univariate and multivariate analysis were unresectable distant metastasis (P= 0.001) and elevated preoperative serum CA 19‐9 (P= 0.02). Patients with synchronous resection of local recurrence and distant metastasis had a significant survival advantage over those without resection of metastases (P= 0.02). Univariate analysis in a subgroup of 26 patients without unresectable distant metastasis revealed pain (P= 0.0003) to be a useful preoperative prognostic indicator, whereas tumor fixation (P= 0.01) and amount of residual tumor after surgical resection (P= 0.01) were significant intraoperative and postoperative factors, respectively. Fluorouracil‐based postoperative systemic chemotherapy produced a significant survival benefit (P= 0.04).CONCLUSIONS:Patients with unresectable distant metastasis are not suitable candidates for surgical resection and intraoperative radiation therapy, whereas those with resectable metastasis are potential candidates. Intraoperative radiation therapy may be less useful for patients with pain, elevated preoperative CA19‐9, fixed tumors, or gross residual tumor after surgical resection. Multimodal treatment strategies combining preoperative and/or postoperative external beam radiation therapy and intraoperative radiation therapy with fluorouracil‐based systemic chemotherapy are recommended for patients with these indicators.