Purpose: To investigate the prognostic value of occult metastases detected by quantitative measurements of candidate biomarkers in sentinel lymph nodes (SLNs) from patients curatively resected for colon cancer.
Methods: Resection specimens from consecutive patients undergoing surgery for localized colon cancer were subjected to ex vivo SLN mapping. SLNs were examined for the presence of metastases by routine hematoxylin-erythrosin-safranin (HES) staining and by CK20 and MUC2 mRNA quantification. The patients were stratified according to KRAS / BRAF mutation status and microsatellite instability status in their primary tumors. Survival end-points were analyzed by Kaplan-Meier survival estimates and log-rank tests.
Results: A total of 817 SLNs were identified in 206 (97%) of the 213 included patients. Routine histological examination of SLNs and other regional lymph nodes identified 63 patients with positive nodes (pN+), of which 42 (67%) were positive in one or more SLNs (sensitivity 67%, false negative rate 33%). Based on the CK20 and MUC2 mRNA levels in SLNs, occult metastases were suggested in 86 (60%) and 52 (36%) of the 143 otherwise LN negative (pN0) patients, respectively. Survival analysis with a median 3.6-year follow-up revealed that MUC2 mRNA quantification had significant prognostic value in SLNs from all patients; however, occult SLN metastasis detection did not.
Conclusions: Occult SLN metastases detected by CK20 and MUC2 mRNA quantification had limited prognostic value.
