Value of RT-PCR analysis of sentinel nodes in determining the pathological nodal status in colon cancer

Background: Pathological examination of sentinel lymph nodes (SLNs) and non-SLNs in colon cancer is frequently not performed to the same extent. We examined whether non-SLNs were truly negative in tumors with tumor-negative SLNs using reverse transcriptase-polymerase chain reaction (RT-PCR). Patients and Methods: RT-PCR with carcinoembryonic antigen (CEA) was performed in hematoxylin-eosin (H&E) and immunohistochemical (IHC) tumor-negative SLNs. In RT-PCR negative SLNs, we also performed RT-PCR on non-SLNs. Statistical analyses indicated the requirement for a minimum of 72 accurate comparisons of non- SLNs and SLNs, which could be fulfilled using tissues from 12 patients. Results: Negative and positive controls were performed. In nine of the 12 colon tumors, H&E and IHC-negative SLNs were also negative with CEA-RT-PCR. A total of 102 lymph nodes, including 99 non-SLNs were retrieved in these nine specimens and none of the non-SLNs were CEA RT-PCR-positive. Conclusion: In this study, all CEA RT-PCR tumor-negative SLNs correctly reflect the tumor-negative status of the non-SLN's in primary colon tumors. The reliability of this method in colon cancer seems promising.