Effect of preoperative radiochemotherapy on lymph node retrieval after resection of rectal cancer.

HYPOTHESIS Preoperative radiochemotherapy for advanced rectal cancer results in fewer lymph nodes detected in the tumor-bearing specimen. DESIGN Nonrandomized control trial with analysis of a prospective perioperative database. SETTING Department of Surgery of a large-volume university hospital. PATIENTS All patients who underwent conventional open surgery to cure rectal cancer between January 1, 1996, and March 31, 2001. INTERVENTIONS During the study period 184 patients (81%, control group) underwent surgery without receiving preoperative radiochemotherapy. Forty-two patients (19%, study group) who had advanced rectal cancer (modified Dukes stages B [tumors that have penetrated the muscle layer of the bowel wall or have gone through the bowel] or C [tumors that have spread to the lymph nodes in the same region]) received preoperative radiochemotherapy (2 cycles of fluorouracil, 4500 rad) during this period. Most patients underwent anterior rectal resection in both groups (77.7% of those who did not receive preoperative radiochemotherapy and 71.8% of those who did), the remaining patients were treated with abdominoperineal resection. RESULTS A mean (SEM) of 19 (1) lymph nodes per specimen were detected in the control patients, while significantly fewer lymph nodes were detected in study patients (13 [1]; P<.05). The rate of inadequate lymph node staging (pNx) increased from 7% in the control group to 12% in the study group (P =.06). Pathological lymph node staging disclosed that significantly more study patients who received preoperative radiochemotherapy had modified Dukes stage A (tumors that are found only in the inner wall or rectum) cancer when compared with the control group (17% vs 0%, respectively; P<.05). CONCLUSIONS Preoperative radiochemotherapy for advanced rectal cancer results in a significant decrease of lymph nodes detected within the tumor-bearing specimen. Preoperative radiochemotherapy induces significant downstaging with fewer positive lymph nodes and more patients presenting with Dukes stage A rectal cancer. Great care must be taken to remove an adequate number of lymph nodes and more sophisticated pathological techniques of lymph node detection are required since the tumors of ever-increasing numbers of patients are inadequately classified.