Tumor regression in mesorectal lymphnodes after neoadjuvant chemoradiation for rectal cancer.

AIMS: The histological modification produced by neoadjuvant chemoradiation on primary rectal cancer has been investigated by many authors, and a prognostic value of tumor regression grade (TRG) has been identified. Tumor regression grade on metastatic mesorectal lymphnodes has been never evaluated. The purpose of this study is to analyse the TRG on mesorectal lymphnodes (lymphnode regression grade, LRG) after preoperative chemoradiation in rectal cancer patients and to determine the correlation with TRG of primary tumor.

METHODS: Surgical specimens from 35 patients who underwent chemoradiation were included. LRG on mesorectal lymphnodes was assessed by immunohistochemistry. Response to treatment was evaluated by a 5-point LRG based on the ratio of residual tumor to fibrosis.

RESULTS: Complete pathologic response (LRG 1) was observed in 18 patients (51%). In 4 patients (11%) no regression was observed (LRG 5). In 4 cases only reactive lymphnodes were found. LRG on lymphnodes significantly correlated with TRG on primary tumor (p<0.05).

CONCLUSIONS: Neoadjuvant chemoradiation determines a tumor regression on mesorectal lymphnodes as on primary tumor; further studies are needed to evaluate the prognostic value of LRG.