Ex Vivo Intra‐arterial Methylene Blue Injection in Rectal Cancer Specimens Increases the Lymph‐Node Harvest, Especially After Preoperative Radiation

Abstract

The use of methylene blue staining of rectal carcinoma preparations leads to a significant increase in the number of lymph nodes examined after neoadjuvant RCT. This can be expected to improve the accuracy of lymph-node staging of neoadjuvant-treated rectal carcinoma.

Advanced Lymph Node Staging With Ex Vivo Intra-arterial Indigo Carmine Injection After Transanal Total Mesorectal Excision for Rectal Cancer: A Retrospective Cohort Study

“…All previous studies assessing ex vivo intra-arterial staining in colorectal cancer have used methylene blue. [8][9][10][11][12][13][14] However, the present study indicates that IC is a possible alternative to methylene blue in advanced lymph node staging of rectal cancer. For ex vivo use, both dyes are effective and pose no risk to the patient.…”

“…The studies assessing methylene blue injections found that staining techniques have no impact on the number of positive lymph nodes or the nodal stage. 9,12–14 Even in small lymph nodes (≤4 mm), staining techniques did not seem to increase the number of identified metastasis. 14 The results of the present study support these findings.…”

“…Similarly, Münster et al observed a significant increase in the lymph node count with the use of ex vivo methylene blue staining in 35 rectal cancer patients after CRT. 13…”

“…[5][6][7] Ex vivo intra-arterial lymph node staining increases the number of identified nodes after colorectal cancer surgery. [8][9][10][11][12][13][14] Instead of the commonly used methylene blue, we used indigo carmine (IC) for staining, which seems to be less mutagenic when used in vivo. 15 Little is known about the effect of ex vivo staining of rectal cancer specimens after neoadjuvant therapy.…”

“…Ex vivo intra-arterial lymph node staining increases the number of identified nodes after colorectal cancer surgery. 8–14 Instead of the commonly used methylene blue, we used indigo carmine (IC) for staining, which seems to be less mutagenic when used in vivo. 15…”