Temporal Trends in Lymph Node Harvest for Oncologic Resection of Stage II and III Colon Cancer
George Q. Zhang*, Joshua Kang, Vanessa Welten, Jennifer Irani, Nelya Melnitchouk, James Yoo, Ronald Bleday, Joel Goldberg
Surgery, Brigham and Women's Hospital, Boston, MA
Objectives: Consensus guidelines implemented in 2007 recommend a minimum of 12 lymph nodes (LN) for oncologic resection of colon cancer to ensure accurate staging. However, recent evidence suggests that a higher yield may influence treatment decisions and more accurately predict outcomes, particularly in locally advanced disease and those with poor histology. Despite this, practice patterns regarding LN harvest are still poorly understood. This study aimed to define trends in LN harvest during colectomy, particularly in the context of the 2007 consensus, as well as demographic, clinical, and oncologic factors associated with greater LN yield.
Design: This was a retrospective cohort study using the National Cancer Database (NCDB).
Setting: The NCDB includes hospital data from Accredited Commission on Cancer facilities across the United States.
Patients: Adult patients with a primary diagnosis of Stage II or III colon adenocarcinoma who underwent colonic resection between the years 2004 and 2016 were included.
Main Outcome Measure (s): Temporal trends in LN harvest, and factors affecting gross and positive LN harvest number. Temporal analysis and multivariable linear regression models were used.
Results: The median number of LN harvested per colectomy increased during our study period, from 15.3 to 22.7 (Figure 1), although the number of positive LN did not vary significantly. Furthermore, the proportion of colectomies with less than 12 lymph nodes harvested decreased from 34% to 15% after implementation of the 2007 consensus guidelines (Figure 2). Upon adjusting for baseline demographic and clinical variables, factors that impacted LN harvest included year of harvest (Ref: 2007 and Before, After 2007: β = 3.20, p<0.001), tumor differentiation (Ref: Well-differentiated, Poorly-differentiated: β = 1.29, p<0.001), and positive margin (Ref: Negative, β = 1.54, p<0.001).
Conclusions: The quantity of LN harvest during colectomy for grade II and III colon cancer is increasing. Surgeon, pathologist, and tumor factors may all impact this outcome. The established 2007 quality metric seems to have further driven LN harvest as well. Additionally, high grade tumors and positive margins are associated with increased LN harvest during colectomy, highlighting its perceived importance in advanced disease.
Figure 1. Trend in median number of lymph nodes harvested and positive per colectomy, by year of surgery (2004 - 2016).
Figure 2. Distribution of lymph node harvest during colon cancer resection, by 2007 Cutoff.
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