ADJUVANT RADIATION-THERAPY IN RESECTABLE RECTAL-CANCER - SHOULD LOCALRECURRENCE 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. Howev er, these series' reported local recurrence rates are 18 to 39 per cen t in the nonradiated patients, which seems extraordinarily high compar ed to the 3 to 5 per cent rates reported by surgeons advocating procte ctomy with complete mesorectal excision. This fact, coupled with the h igh cost of XRT ($11,000-$14,000), the risk of radiation injury to sma ll bowel and the neo-rectum, and the failure of XRT to provide any sur vival advantage, raises questions as to the precise role of XRT for re ctal cancer. The purpose of this study was to perform a review of 212 consecutive patients undergoing curative resection via low anterior re section (LAR) or abdominoperineal resection (APR) for rectal cancer be tween 1989 and 1993, focusing on local and distant recurrence rates an d 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:f emale 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) betwee n the groups. There were no significant differences in age between the preoperative and postoperative radiation groups (PRE, 64.0 +/- 2.4; P OST, 59.2 +/- 1.7); however, age was significantly different (P < 0.05 ) between the surgery-alone and the postoperative radiation groups (SU R, 68.5 +/- 0.8; POST, 59.2 +/- 1.7). With a median follow-up of 49 mo nths, there were no significant differences in local recurrence (SUR, 4.2%; PRE, 4.5%; POST, 2.1%); however, there was a significantly longe r survival for the SUR group compared to the other groups (SUR, 45.9 m onths; 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 49; P RE, 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 procte ctomy with complete mesorectal excision yields a 4.2 per cent local re currence rate without the need for adjuvant XRT. In this series, if al l the patients had received adjuvant radiation, an additional $2.2 mil lion would have been added to the costs of medical care. Therefore, th e potential risks, costs, and benefits of adjuvant pelvic XRT for rect al cancer must be weighed against optimal benchmarks for local recurre nce rate for surgery alone.