Prediction of lateral pelvic node involvement in low rectal cancer by conventional computed tomography

Background: The clinical significance of lateral pelvic lymphatic spread in rectal cancer remains unknown. The present study aimed to assess the accuracy of preoperative computed tomography (CT) for prediction of lateral node involvement in patients with low rectal cancer and to determine the prognostic significance of extended lateral node dissection. Methods: A total of 109 patients with primary low rectal cancer were enrolled in this prospective cohort study. The preoperative CT findings were compared with the histopathological results and with follow-up data. Results: CT diagnosed lateral lymph node status with high accuracy (sensitivity 95 per cent, specificity 94 per cent), in marked contrast to mesorectal node status. Of 68 patients who had RO resection without lateral node dissection, only two developed pelvic wall recurrence during median follow-up of 4.1 years. Metastatic nodes in the lateral pelvic region were significantly larger than those in the mesorectum (P < 0.001). Conclusion: CT accurately predicted lateral lymph node status in low rectal cancer, allowing preoperative identification of patients who might benefit from extended lateral node dissection.