Purpose: This study was designed to clarify indication and benefit of pelvic sidewall dissection for rectal cancer.
Methods: The retrospective, multicenter study collected the data of rectal cancer patients who underwent surgery between 1991 and 1998 and were prospectively followed.
Results: Of 1,977 patients with rectal cancers, 930 underwent pelvic sidewall dissection without adjuvant radiotherapy. Positive lateral lymph nodes were found in 129. Multivariate analysis disclosed a significantly increased incidence of positive lateral lymph nodes in female gender, lower rectal cancers, non-well-differentiated adenocarcinoma, tumor size of > or =4 cm and T3-T4. The five-year survival rate for 1,977 patients was 79.7 percent. The survival of patients with positive lateral lymph nodes was significantly worse than that of Stage III patients with negative lateral lymph nodes (45.8 vs. 71.2 percent, P<0.0001). Multivariate analysis showed significantly worse prognosis in male gender, pelvic sidewall dissection, lower rectal cancers, T3-T4, perirectal lymph node metastasis, and positive lateral lymph nodes. During the median follow-up time of 57 months, recurrence developed in 19.7 percent: 17 percent in negative and 58.1 percent in positive lateral lymph nodes (P<0.0001). Local recurrence was found in 8 percent: 6.8 percent in negative and 25.6 percent in positive lateral lymph nodes (P<0.0001). Multivariate analysis disclosed that lower rectal cancers, non-well-differentiated adenocarcinoma, T3-T4, perirectal lymph node metastasis, and positive lateral lymph nodes were significantly associated with an increased local recurrence.
Conclusions: Positive lateral lymph node was the strongest predictor in both survival and local recurrence. Pelvic sidewall dissection may be indicated for patients with T3-T4 lower rectal cancers because of the greater probability of positive lateral lymph nodes.