Pathological evaluation of mesocolic resection quality and ex vivo methylene blue injection: what is the impact on lymph node harvest after colon resection for cancer?

BACKGROUND: Although the National Quality Forum has endorsed the harvest of ≥12 lymph nodes as a standard quality indicator for colon cancer surgery, this minimum quantity is not reached in many centers.

OBJECTIVE: The aim of this study was to assess the impact of the implementation of a mesocolon evaluation pathological protocol and ex vivo arterial methylene blue injection on the number of nodes harvested after colon cancer resection.

DESIGN: A prospective series was compared with a historical group.

SETTINGS: This study was conducted by a specialized colorectal multidisciplinary team at a tertiary teaching hospital.

PATIENTS: From June 2009 to December 2009, all the specimens after colon resection for cancer were analyzed with the use of a "mesocolon quality pathological evaluation" protocol. Moreover, a consecutive series of specimens was analyzed after arterial ex vivo injection of methylene blue. We compared the study groups with our previous series (2005-2009).

INTERVENTIONS: The "mesocolon quality pathological evaluation" protocol was used with or without arterial methylene blue ex vivo injection.

MAIN OUTCOME MEASURE: The primary outcome measure was the number of lymph nodes harvested.

RESULTS: The mean number (SD) of lymph nodes collected was 20.6 (10.5), 37.1 (12.8), and 47.6 (12.9) (p < 0.0001) in the control, protocol, and methylene blue groups. In the control group, the minimum number of 12 and 18 lymph nodes collected was not reached in 92 (15.9%) and 258 (44.6%) patients. In contrast, all patients in the protocol and methylene blue groups had more than 18 lymph nodes collected. The multivariate analysis confirmed the application of the "mesocolon quality pathological evaluation" protocol and the methylene blue ex vivo injection, along with the type of resection and the length of the specimen, to be independent factors determining the number of nodes collected.

LIMITATIONS: The patients are not randomly selected and are compared with a retrospective series.

CONCLUSION: The implementation of a "mesocolon quality pathological evaluation" protocol along with the arterial ex vivo injection of methylene blue can significantly increase the number of nodes isolated after colonic resection, reaching a 100% rate of specimens with more than 12 nodes.