Phase I study on sentinel lymph node mapping in colon cancer: a preliminary report

Area of Science:

• Oncology
• Surgical Pathology
• Cancer Diagnostics

Background:

• Lymph node metastasis is a critical prognostic factor in colorectal cancer.
• Conventional pathological examination may underestimate lymph node-positive cases.
• Sentinel lymph node (SLN) identification is crucial for accurate staging and treatment decisions.

Purpose of the Study:

• To evaluate the feasibility of a novel, harmless coloration technique for identifying sentinel lymph nodes (SLNs) in colorectal cancer patients.
• To assess the potential impact of SLN identification on initial cancer staging.

Main Methods:

• A subserosal peritumoral injection of lymphazurin 1% was administered to 20 colorectal cancer patients prior to resection.
• Pathologists immediately examined specimens to identify and harvest colored SLNs.
• SLNs were analyzed using serial sectioning with H&E staining and immunohistochemistry (AE1-AE3 cytokeratin markers).

Main Results:

• SLNs were identified by pathologists in 90% of cases, though preoperative identification was not always possible.
• The average number of identified SLNs per patient was 3.9.
• Immunohistochemical analysis of SLNs led to a potential staging upgrade from Dukes B to Dukes C in 25% of patients (5 out of 20).
• One patient (5%) with hepatic metastasis had negative SLN pathology, indicating skip metastasis.

Conclusions:

• Sentinel lymph node biopsy is feasible in colorectal cancer, with successful SLN identification in at least 90% of patients.
• The technique revealed tumor cells in SLNs for 45% of patients initially staged as Dukes B, resulting in a 25% overall staging upgrade.
• Further research is needed to clarify the clinical significance and metastatic potential of small tumor cell clusters found in SLNs.