Time-Dependent Trends in Lymph Node Yield and Impact on Adjuvant Therapy Decisions in Colon Cancer Surgery: An International Multi-Institutional Study

Lymph node yield (LNY) and accuracy of nodal assessment are critical to staging and treatment planning in colon cancer (CC). A nationally agreed upon 12-node minimum is a quality standard in CC. The impact of this quality measure on LNY and impact on therapeutic decisions are evaluated in two international, multi-center, prospective trials comprising a well-characterized cohort assembled over 8 years (2001-2009) with long-term follow-up. Quality adherence through increased LNY improves staging accuracy and impacts adjuvant therapy decisions. Retrospective analysis of prospective data to assess time-dependent LNY, the dependent variable in multivariate linear regression analysis adjusted for age, gender, body-mass-index (BMI), tumor size/stage/grade, anatomic location and surgery date. Two-hundred-forty-five patients with non-metastatic CC, median age 70 years, BMI 26 kg/m(2), tumor size 4.0 cm, and LNY 17 nodes were studied. Seventy-two percent had T3 (70 %)/T4 (2 %) tumors. Adherence to the 12-node minimum was 70 %(2001-2002), 81 % (2003-2004), 90 % (2005-2006), 94 % (2007-2008). LNY significantly increased over time (Median LNY: 2001-2004 = 15 vs. 2005-2008 = 17; P < 0.001) on multivariate analysis controlling for tumor size (P < 0.001), and right-sided tumor location (P < 0.001). Adjuvant therapy administration and indication for chemotherapy according to LNY (< 12 vs. 12 + LNs = 33 % vs. 39 %; P = 0.48) and time period (2001-2004 vs. 2005-2008 = 39 % vs. 37 %; P = 0.89) remained unchanged. Despite the independent predictors of nodal yield (tumor location and size), year of study still had a significant impact on nodal yield. Despite increased quality adherence and LNY over time, there appears to be a delayed impact on adjuvant therapy decisions once quality standard adherence takes effect.