Lymph node number, surface area and lymph node ratio are important prognostic indicators in neoadjuvant chemoradiotherapy treated rectal cancer.

Aims Neoadjuvant chemoradiotherapy (neoCRT) is recommended for locally advanced rectal cancer (RC), however, this often makes lymph node (LN) search trying. The aim of this study was to evaluate, in a large retrospective, monocentric, series of post-neoCRT-RC patients, the importance of LN number, ratio and surface area in predicting metastases, overall survival (OS) and disease free survival (DFS). Methods 104 patients with RC underwent total mesorectal excision, after standard neoCRT. All resected specimens were examined according to a standardised sampling/histopathological protocol. The following data regarding LNs were collected: total numbers; number with metastases; LNratio (metastatic/total); maximum diameter; surface area. Results A statistically significant association was found between LN number and DFS (p=0.0473). Finding <= 9 or >20 LNs correlated with worse prognosis compared with 10-20 (p value=0.049). LNratio (>0.2) was strongly associated with shorter DFS (HR=13.36; p value <0.0001) and OS (HR=26.06; p value <0.0001). Poor outcome, for DFS (HR=2.17, p value =0.0416) and OS (HR=1.18, p value =0.0025), was associated with increasing LN surface area. LNratio was independently associated with DFS at multivariate analysis (p value <0.0001). Conclusions LN number, LNratio and LN surface area are important prognostic factors in neoCRT-RC and in particular finding <= 9 or >20 LNs is prognostically adverse.