Adjuvant radiation therapy in resectable rectal cancer: should local recurrence rates affect the decision?

Adjuvant external beam pelvic radiotherapy (XRT) for resectable rectal cancer has been mandated by the National Cancer Institute because of reported 20 to 50 per cent reductions in local recurrence rates. However, these series' reported local recurrence rates are 18 to 39 per cent in the nonradiated patients, which seems extraordinarily high compared to the 3 to 5 per cent rates reported by surgeons advocating proctectomy with complete mesorectal excision. This fact, coupled with the high cost of XRT ($11,000-$14,000), the risk of radiation injury to small bowel and the neo-rectum, and the failure of XRT to provide any survival advantage, raises questions as to the precise role of XRT for rectal cancer. The purpose of this study was to perform a review of 212 consecutive patients undergoing curative resection via low anterior resection (LAR) or abdominoperineal resection (APR) for rectal cancer between 1989 and 1993, focusing on local and distant recurrence rates and survival. The choice of surgery alone (SUR), preoperative radiation (PRE) (45 Gy), or postoperative radiation (POST) (45-50 Gy) was at the surgeon's discretion. There were no significant differences in male:female ratio (SUR, 83:60; PRE, 14:8; POST, 34:13) or type of procedure (SUR-LAR, 112:APR, 31; PRE-LAR, 5:APR, 17; POST-LAR, 30:APR, 17) between the groups. There were no significant differences in age between the preoperative and postoperative radiation groups (PRE, 64.0 +/- 2.4; POST, 59.2 +/- 1.7); however, age was significantly different (P < 0.05) between the surgery-alone and the postoperative radiation groups (SUR, 68.5 +/- 0.8; POST, 59.2 +/- 1.7). With a median follow-up of 49 months, there were no significant differences in local recurrence (SUR, 4.2%; PRE, 4.5%; POST, 2.1%); however, there was a significantly longer survival for the SUR group compared to the other groups (SUR, 45.9 months; PRE, 36.4 months; POST, 39.3 months; P < 0.05 least significant difference). The PRE group also had shorter survival compared to the other groups when only Stage II and III lesions were studied (S, 40.0 months; PRE, 28.3 months; POST, 39.3 months). Local recurrences based on TNM stage were: T1N0 (S, 0 of 27; PRE, 0 of 3); T2N0 (S, 4 of 4S; PRE, 0 of 7); T2N1 (S, 0 of 9; POST, 1 of 5); T3,4N0 (S, 2 of 37; PRE, 1 of 9; POST, 0 of 10); and T3,4N1,2 (S, 0 of 21; PRE, 0 of 3; POST, 0 of 30). The results of this series support the contention that proctectomy with complete mesorectal excision yields a 4.2 per cent local recurrence rate without the need for adjuvant XRT. In this series, if all the patients had received adjuvant radiation, an additional $2.2 million would have been added to the costs of medical care. Therefore, the potential risks, costs, and benefits of adjuvant pelvic XRT for rectal cancer must be weighed against optimal benchmarks for local recurrence rate for surgery alone.