Abstract 417P
Background
In colon cancer, histology, lymphovascular or perineural invasion (LVI or PNI), bowel obstruction or perforation, <12 examined lymph nodes (LN), and resection margins are known to be high-risk features for recurrence. The number of retrieved LN has increased over time and requires a reassessment of its role. Our goal was to evaluate if LN retrieval is still valid for predicting the recurrence of colon cancer and refine the cut-off point.
Methods
Between 2005 and 2015, we reviewed 3,126 eligible patients with stage II and III colon cancer from the Yonsei Cancer Center (YCC) registry. Logistic regression analysis, Kaplan-Meier method, and Cox regression models were used to analyze 6-year overall survival (OS) and 3-year disease-free survival (DFS). Hazards and odds ratios with 95% confidence interval are reported. Optimal LN yield was evaluated by testing every cut-off from 3 to 165.
Results
In YCC, 5-year survival rate in stage III colon cancer has improved from 60.4% to 78.1% in the past 20 years, and LN retrieval was the only factor significantly associated with years (OR 1.28 [1.23-1.33], p < 0.001) after adjusting for sex, age, operated year, histology, T or N stage, tumor site, LVI or PNI, and margin. The median number of retrieved LNs was 22 (mean 24 ± 14, range 0-112) in stage II, 22 (mean 25 ± 15, range 2-165) in stage III colon cancers. LN count below 12 showed no significance with OS in stage II (HR 1.20, p = 0.335), in stage III (HR 1.34, p = 0.074), and also with DFS in stage II (HR 1.20, p = 0.300), in stage III (HR 1.12, p = 0.449). High histology grade (poorly differentiated adenocarcinoma, mucinous adenocarcinoma, signet ring cell carcinoma), T4 stage, N2 stage, LVI or PNI were all associated with worse OS in stage III (HR 1.55 [1.18-2.04], p = 0.00154; HR 2.65 [2.11-3.32], p < 0.001; HR 1.82 [1.46-2.27], p < 0.001; HR 1.38 [1.11-1.71], p = 0.00400, respectively). LN cut-off analysis in stage III showed that 19, 20, 21 were the only points significant with worse DFS (p = 0.0288, p = 0.0358, p = 0.0258, respectively).
Conclusions
Retrieving more than 12 LNs from surgery is crucial to prevent false negative nodal staging. However, our data suggest that LN count below 12 is not associated with survival in stage II and III colon cancer. Cut-off value of LN retrieval also needs to be re-evaluated.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.