eP419 - Incidence of Lymph Node Metastases in Colon Cancer: Does Primary Tumor Location Matter?

ePoster Presenter(s)

• 

  Lauren Weaver, MD

  General Surgery Resident
  University of Minnesota
  University of Minnesota
  Minneapolis, MN, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.

Author(s)

• SM

  Sarah Mott, MS

  Biostatistician
  University of Iowa
  Iowa City, Iowa, United States

  Disclosure information not submitted.
• JK

  Julia Kohn, MD (she/her/hers)

  Surgery resident
  University of Minnesota
  University of Minnesota
  Minneapolis, MN, United States

  All relevant financial disclosures have been managed and will be listed below.
  This individual has no financial relationships with ineligible companies.
• AP

  Ajay Prakash, MD/PhD

  Assistant Professor
  University of Minnesota
  Minneapolis, Minnesota, United States

  Disclosure information not submitted.
• IH

  Imran Hassan, MD

  Adjunct Clinical Professor
  University of Iowa
  Cedar Rapids, Iowa, United States

  All relevant financial disclosures have been managed and will be listed below.
  This individual has no financial relationships with ineligible companies.
• GM

  Genevieve B. Melton, MD, PhD

  Professor
  University of Minnesota
  Minneapolis, Minnesota, United States

  Disclosure information not submitted.
• 

  Wolfgang Gaertner, MSc, MD, MBA

  Associate Professor and Chief, Division of Colon & Rectal Surgery
  University of Minnesota - M Health
  University of Minnesota
  Minneapolis, Minnesota, United States

  Disclosure information not submitted.

Senior Author(s)

• PG

  Paolo Goffredo, MD

  Assistant Professor
  University of Minnesota
  Minneapolis, Minnesota, United States

  Disclosure information not submitted.

Purpose/Background: Over the past decade, proximal tumor location has been associated with worse oncologic outcomes for colon adenocarcinoma. While the explanation for this observation remains unclear, we hypothesized proximal cancers may present with a more aggressive biology leading to higher rates of lymph node (LN) metastases, and therefore, worse survival outcomes.Methods/Interventions: The National Cancer Database was queried for adults diagnosed with Stage I-III colon adenocarcinoma from 2010 through 2019 who underwent oncologic segmental resection within a year of diagnosis. Patients who underwent neoadjuvant treatment, diagnosed with more than one lifetime cancer, or diagnosed with either appendiceal cancer, rectal cancer, synchronous colon cancer or recurrent cancer were excluded. Also patients who did not have recorded pathologic T or N staging, less than 12 lymph nodes excised, or lacked follow-up data were excluded. Proximal tumor location was defined as a tumor proximal to the splenic flexure. Logistic regression models estimated the effect of patient and tumor characteristics on the likelihood of pathologic nodal involvement expressed as odds ratios with 95% confidence intervals.Results/Outcomes: A total of 82,535 patients (59% < 70 years old, 51% female, 76% white race) met inclusion criteria; 63% had proximal tumors and 37% presented with nodal disease. Node positive cancers were more common in patients < 70 years old (63%) and had a lower proportion of proximal lesions (60% vs 65%) compared to node negative cancers. In the multivariable analysis, non-white patients including Black, Hispanic, and other races were more likely to have lymph node metastases. Also, patients with a moderately or poorly differentiated tumor, mucinous or signet ring cell histology, lymphovascular invasion (LVI), perineural invasion (PNI), and increasing T stage were more likely to demonstrate pathologic LN involvement, whereas age >70 years, microsatellite unstable (MSI-high) status, and proximal location were less often associated with nodal disease (Table 1).Conclusion/

Discussion: In this national cohort, we confirmed the impact of known prognostic factors for LN involvement, including tumor grade and histology, LVI, PNI, and increasing T stage, while older patients and those with MSI-high lesions were less likely to have pathologically confirmed nodal disease. Proximal tumor location was also associated with lower risk of LN metastases; therefore, the worse oncologic outcomes observed for patients with proximal colon adenocarcinomas may not be related to increased rates of early lymph node metastases.Table 1Multivariable analysis on the demographic and tumor characteristics associated with the odds of pathologic lymph node involvement in patients diagnosed with colon adenocarcinoma.