Survival implications of pretreatment pelvic CT in rectal cancer patients after neoadjuvant chemoradiotherapy and surgery.

PURPOSE To determine the correlation between pretreatment computed tomography (CT) data and survival duration after neoadjuvant chemoradiotherapy and surgery for locally advanced rectal cancer. MATERIALS AND METHODS 122 consecutive patients with advanced rectal cancer were assessed retrospectively. Pretreatment imaging and postoperative data were evaluated through Kaplan-Meier and Cox proportional hazard regression analyses. RESULTS Pretreatment CT identified 557 metastatic lymph nodes (mean, 4.55 per patient; median 4). Survival durations were measured during the period between the application of CT and death or the last follow-up examination. Univariate analysis showed that the following factors had a significant impact on survival: maximum tumor diameter (P = 0.019), distance from inferior tumor margin to anorectal ring (P <0.0001), number of lymph nodes involved in patients with short-axis, lymph node diameter ≥8 mm (P <0.0001) in pretreatment CT, distance from the anorectal ring (P = 0.027), ypN stage (P = 0.0008), ypM stage (P = 0.046) and number of metastatic lymph nodes (P <0.0001) in clinical assessment. Multivariate analysis showed that the following factors were significant: number of lymph nodes in patients with short-axis lymph node diameter ≥5 mm but <8 mm (P = 0.044) and in those with this diameter ≥8 mm (P = 0.028; pretreatment CT) and number of metastatic lymph nodes (assessed in histopathological examination). CONCLUSION Pretreatment lymph node size and number can predict survival duration after treatment for locally advanced rectal cancer. For patients with lymph nodes >8 mm (short-axis diameter) and/or >1, such lymph nodes tend to have a poor performance for prognosis.