[Risk factors related to lymph node metastases after neoadjuvant therapy for locally advanced rectal cancer].

BACKGROUND AND OBJECTIVE: Neoadjuvant therapy (radiotherapy, RT or chemoradiotherapy, CRT) could change status of the invasion and lymph node metastasis of rectal cancer. The risk factors of lymph node metastasis in rectal cancers without neoadjuvant therapy have been well known, but those in rectal cancers treated with preoperative RT or CRT remain unclear. This study was to investigate the risk factors of lymph node metastasis in patients who underwent preoperative RT or CRT for rectal cancers.

METHODS: Clinical data of 93 patients underwent preoperative RT or CRT followed by total mesorectal exesion (TME) for locally advanced rectal adenocarcinoma from August, 2003 to February, 2008 were reviewed. Twelve clinicopathologic factors and treatment-related factors were studied with univariate and multivariate analyses.

RESULTS: Univariate analysis showed that post-RT or post-CRT serum carcinoembryonic antigen (CEA) level, radiation dose, time interval from RT or CRT to TME, concurrent chemotherapy with oxaliplatin-containing regimens, and infiltration extent to bowel wall after RT or CRT (ypT stage) were significantly associated with lymph node status after RT or CRT (ypN stage). Multivariate analysis showed that concurrent chemotherapy with oxaliplatin-containing regimens (r=-0.481, P<0.01) and ypT stage (r=0.503, P<0.01) were independent risk factors of ypN stage.

CONCLUSIONS: Pathologic T stage is the most reliable predictor of lymph node stage in rectal cancer patients received preoperative RT or CRT. Oxaliplatin-containing regimens could significantly reduce the risks of lymph node metastases and potentially improve the prognosis.