Population-based study to re-evaluate optimal lymph node yield in colonic cancer.

Area of Science:

• Oncology
• Surgical Pathology
• Cancer Research

Background:

• Lymph node (LN) yield in colon cancer resection is a known prognostic factor.
• Optimal LN yield for accurate staging and improved survival remains unclear.
• This study evaluates LN thresholds for LN positivity and survival in a population-based colon cancer cohort.

Purpose of the Study:

• To determine the optimal lymph node (LN) yield for accurate staging in colon cancer.
• To identify LN yield thresholds associated with improved cancer-specific survival (CSS).
• To evaluate the prognostic significance of LN yield in stages II and III colon cancer.

Main Methods:

• Utilized a 25% random sample of stage II/III colon cancer patients from the Ontario Cancer Registry (2002-2008).
• Employed multivariable regression to identify factors associated with LN positivity.
• Applied Cox models and sequential regression analysis to determine LN thresholds for CSS.

Main Results:

• Greater LN yield was associated with increased likelihood of LN positivity, with diminishing returns beyond 12-14 LNs.
• Lower LN yield significantly increased cancer-specific mortality risk in stage II disease (HR 1.55-1.74), with no survival benefit beyond 20 LNs.
• Lower LN yield also increased CSS risk in stage III disease (HR 1.49-2.20), with no specific survival threshold identified.

Conclusions:

• Optimal LN evaluation for colon cancer shows incongruity between staging and survival metrics.
• A threshold of 12 LNs may suffice for accurate staging.
• Higher LN yields, potentially exceeding 20 LNs, are linked to improved survival outcomes.