Sentinel lymph nodes of colorectal carcinoma: Reappraisal of 123 cases

Aims - Results concerning the usefulness of the sentinel lymph node (SLN) in colorectal carcinoma have been discordant. The SLN technique may be used to guide surgical resection (lymph mapping), restrict the lymph node analysis solely to the SLN (accuracy) and upgrade tumor staging when micrometastases are specifically detected in the SLN. Methods - The blue dye injection technique was used. Serial sections of the SLNs were analyzed after hematoxylin-eosin (HES) staining. Results - The SLN technique was tested in 123 patients, successfully in 112/118 (feasibility 95%) (five intraoperative exclusions). On average, twenty lymph nodes (range: 5-74) and two SLNs (range: 1-5) were identified. Lymph mapping was used in 11% of patients to guide surgical resection; the SLN was negative in 14 of 36 N+ patients (39% false-negatives); HES staining enabled detection of micrometastases in 8 of 84 initially N0 patients (10% secondary upgrading to N+). Conclusion - Limiting node analysis to the SLN cannot replace a complete pathology examination of all resected lymph nodes. Careful examination of serial sections of the SLN can however affect therapeutic decision making since staging may be upgraded in up to 10% of initially N0 patients.