EP630 - Assessing Variation in Suboptimal Lymph Node Yield for Colon and Rectal Cancer: Attributable to the Surgeon, Pathologist, or Hospital?

Purpose/Background: A lymph node yield of at least 12 lymph nodes has been established as a quality metric for colorectal cancer. While prior studies have evaluated variation in suboptimal lymph node yield for colon cancer, those studies are outdated, and there is currently little information regarding variation in lymph node yield for rectal cancer.

Methods/Interventions: Patients >65 years old who underwent stage I-III colon or rectal cancer resection between 2009-2022 were identified within SEER-Medicare. Multilevel logistic regression analyses assessed factors associated with suboptimal lymph node yield ( < 12 lymph nodes examined) as well as the proportion of variation attributable to the surgeon, pathologist, and hospital.

Results/Outcomes: Among 59,219 colon and 7,696 rectal cancer resections, the rate of suboptimal lymph node yield was 16.3% for colon cancer and 35.5% for rectal cancer. In comparing 2009-2012 and 2018-2022, there was significant improvement in suboptimal lymph node yield for colon cancer (21.9% vs 10.7%, p< 0.0001) but only modest improvement for rectal cancer (40.1% vs 31.8%). Factors associated with suboptimal lymph node yield for both colon and rectal cancer included patient race, socioeconomic status, comorbidity burden, neoadjuvant therapy, non-elective surgery, procedure type, operative approach, and year of surgery (Table). Receipt of total neoadjuvant therapy with both radiation and chemotherapy for rectal cancer appeared to have an additive effect. After risk-adjustment, the majority of unexplained variation was attributable to hospitals for both colon (59.6%) and rectal (69.9%) cancer, and less so to pathologists (25.7% and 23.2%, respectively), with very little unexplained variation attributable to surgeons (14.6% and 6.9%, respectively).

Conclusion/Discussion: While the rate of suboptimal lymph node yield has significantly improved for colon cancer, the rate remains high for rectal cancer. Increased use of neoadjuvant therapy for rectal cancer, especially total neoadjuvant therapy, appears to contribute to this limited improvement. Furthermore, only a small proportion of unexplained variation is attributable to surgeons and pathologists. These findings suggest that a quality metric with a defined lymph node yield for rectal cancer may not be appropriate, and efforts to improve lymph node yield should be focused on the systems-level rather than individual surgeons or pathologists.

Factors Associated with Suboptimal Lymph Node Yield following Colorectal Cancer Resection