Impact of Schwartz enhanced visualization solution on staging colorectal cancer and clinicopathological features associated with lymph node count

BACKGROUND Stage-specific survival for colon cancer improves when more lymph nodes are reported in the surgical specimen. This has led to a minimum standard of identifying 12 lymph nodes as a quality indicator. OBJECTIVE The aim of this study was to determine whether the addition of Schwartz solution increases node yield and impacts pathologic staging. DESIGN This is a prospective cohort study. SETTING The study was conducted in an academic medical center. PATIENTS Included were 104 consecutive patients with colorectal cancer. MAIN OUTCOME MEASURES Lymph node counts before and after specimen treatment with Schwartz solution and incidence of upstaging were measured. RESULTS An additional 20 minutes (interquartile range, 15-40 minutes) was spent searching for lymph nodes, increasing the median number of nodes from 22.5 to 29.0 nodes. However, only 1 patient was upstaged. Schwartz solution decreased the number of specimens with less than 12 lymph nodes from 15 to 6. The following factors were associated with Schwartz solution leading to the detection of additional nodes: number of nodes detected initially with formalin only (p < 0.000), mesenteric fat volume (p < 0.000), mesenteric fat weight (p < 0.000), length of specimen (p < 0.016), tumor greatest dimension (p < 0.016), patient body surface area (p < 0.034), and patient age (p < 0.003). LIMITATIONS Clinical data for this study were obtained retrospectively and were not available for all of the patients. CONCLUSIONS Although Schwartz solution increased the number of nodes detected in 95% of patients and improved compliance with the 12-node standard for colon resection, there was minimal impact on cancer staging. Upstaging is unlikely to explain the increase in overall survival in patients with higher lymph node counts, casting doubt on the validity of this process measure as a meaningful quality indicator. Rather, the lymph node count may be a reflection of inherent tumor biology or host-related factors.