Total number of lymph nodes harvested is associated with better survival in stages II and III colorectal cancer.

Background: Lymph node status is important in staging colorectal cancer (CRC). Presence of metastatic nodes differentiates stage III from stage II. The role of adjuvant therapy is still unclear in stage II CRC. Inadequate node sampling may result in inaccurate staging.

Method: Records of 131 patients with stages II and III CRC who underwent curative resection, having five or more lymph nodes harvested from the specimen, were prospectively followed up and analyzed. The Kaplan-Meier method was used to analyze survival, based on groups of serially ascending values of lymph nodes harvested. Regression analysis was performed by Cox proportional hazards ratio model with right-censored CRC survival data at a 10 % significance level. The effect of nodal harvest on survival was adjusted for age, sex, preoperative carcinoembryonic antigen (CEA) level, neoadjuvant chemoradiation, pathological tumor stage, histological type, differentiation, margin positivity, angioinvasion, perineural invasion, and lymphovascular infiltration.

Results: The total population showed improved survival with 14 or more nodes harvested (p= 0.005). For both rectal (n= 83; p= 0.03) and colon cancers (n= 46; p= 0.08), most significant survival benefits were seen with over 14 nodes harvested, irrespective of the stage. With multiple regression analysis, advanced age (p= 0.003), male sex (p= 0.017), lymphovascular infiltration (p= 0.015), and preoperative CEA levels (p= 0.096) were found to be other significant factors. The lymph node effect remained significant (HR = 0.19, p= 0.004) after adjusting for the above factors.

Conclusion: A lymph node harvest of 14 or more resulted in better survival outcome from CRC in this population. Staging of the disease could be accurate with increased nodal harvesting.