Abstract
Iliopelvic lymphadenectomy associated with low anterior resection or rectal amputation was performed on 171 patients with rectal cancer. Lymph node metastases were found in 26 of them (15.2%), and the metastatic lymph nodes were histologically well or moderately differentiated adenocarcinoma in 23 of the 26. In these 23 cases, the longest distance from dentate line to anal edge of the tumor was 6 cm in 3 patients with cancer invasion limited to the proper muscle layer, and 9 cm in 20 patients with invasion beyond the layer. The distance was as long as 12 cm in 3 patients with poorly differentiated adenocarcinoma. These results suggest that the indication for iliopelvic lymphadenectomy could be based on the histologic type, depth of cancer invasion and distance from dentate line to anal edge of the tumor. Furthermore, contralateral lymph node metastases were not found when the tumor was unilaterally or partially bilaterally confined to the right or left side of the rectal wall, occupying less than half of the circumference. A unilateral autonomic nerve-preserving operation dissecting only iliopelvic lymph nodes of the tumor side would be justified for these cases. However, metastases jumping to iliopelvic lymph nodes were demonstrated in 5 of the 26 cases, suggesting the necessity of wide lymph node dissection in some cases.
