Prognostic impact of the number of lymph nodes examined in different stages of colorectal mucinous adenocarcinoma.

Abstract

BackgroundMucinous adenocarcinoma (MC) is a special kind of colorectal adenocarcinoma that occurs more frequently in young patients and females, but the prognostic effect of lymph nodes in MC patients is unclear. This population-based study was conducted to analyze the prognostic value of the number of lymph nodes examined in different stages of colorectal MC.MethodsWe included 17,001 MC patients from the Surveillance, Epidemiology, and End Results program database between 2003 and 2013, of which 12,812 (75%) had >12 lymph nodes examined.ResultsCompared to the group with insufficient lymph nodes examined, patients with more lymph nodes (>12) examined tended to come from east and central America, were more frequently female and young, were diagnosed after 2008, had larger-sized tumors of less differentiated grade and in later stages, had not received radiation therapy and had more positive nodal status. Patients with more lymph nodes (>12) examined demonstrated significantly better survival than those with insufficient lymph nodes examined only in stages II and III (stage II: overall, P<0.001; cancer-specific, P<0.001; stage III: overall, P=0.093; cancer-specific, P=0.032), even though the overall (P<0.001) and cancer-specific survival (P<0.001) showed significant differences between the two groups. Both univariate (overall, HR=0.739, 95% CI=0.703–0.777, P<0.001; cancer-specific, HR=0.742, 95% CI=0.698–0.788, P<0.001) and multivariate (overall, HR=0.601, 95% CI=0.537–0.673, P<0.001; cancer-specific, HR=0.582, 95% CI=0.511–0.664, P<0.001) Cox proportional hazards models verified the association between >12 lymph nodes examined and better survival.ConclusionMore number of lymph nodes (.12) examined significantly increased the survival probability of MC patients in stages II and III, but had no significant influence on patients in stages I and IV, indicating the effect of number of lymph nodes examined was a stage-dependent prognostic factor in clinical utility.