A prospective study of false-positive diagnosis of micrometastatic cells in the sentinel lymph nodes in colorectal cancer.
BACKGROUND
Sentinel lymph node mapping (SLNM) with multilevel sections (MLS) and cytokeratin immunohistochemistry (CK-IHC) of sentinel lymph nodes (SLNs) upstages 15-20% of patients (pts). False-positive SLNs occur in breast cancer due to mechanical transport of cells during mapping procedures, or to pre-existing benign cellular inclusions. Our prospective study evaluated whether colorectal mapping procedures alone caused false positives.


METHODS
A total of 314 pts underwent SLNM with blue dye. Ninety of the pts underwent a second mapping in normal bowel away from the primary tumor. The first 1-5 blue nodes near the primary tumor were marked as SLNs; those near the second injection site were marked as nontumor SLNs (nt-SLNs). All SLNs and nt-SLNs were evaluated by MLS and CK-IHC.


RESULTS
Of 314 pts, 30 had benign tumor and 284 had invasive cancer. SLNM was successful in 274/284 (96.5%) invasive cancer pts, with 728 SLNs identified. Forty-six of the 274 pts (16.8%) had low-volume metastasis in 57 SLNs: 31 pts (11.3%) had 38 SLNs with micrometastasis (>0.2 mm, <or=2 mm), while 15 pts (5.5%) had 19 SLNs with isolated tumor cells (<or=0.2 mm). For 100 pts with second SLNM (70/90 pts successfully mapped with 102 nt-SLNs), or with SLNM of benign pathology (30/30 pts successfully mapped with 88 SLNs), there were no false positives in any of 190 nodes (P < 0.001).


CONCLUSIONS
No false positives due to mechanical transport of cells or to benign cellular inclusions were identified in 190 lymph nodes from 100 patients with SLNM in benign bowel.
Department of Pathology, Michigan State University, McLaren Regional Medical Center, Flint, MI, USA. dr.davew@comcast.net
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Wiese
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Saha
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Yestrepsky
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Korant
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Sirop
D015179:Colorectal Neoplasms / Q000556:secondary* / Q000601:surgery; D005189:False Positive Reactions; D006498:Hepatectomy; D006801:Humans; D007633:Keratins / Q000378:metabolism; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D021701:Sentinel Lymph Node Biopsy; D015996:Survival Rate; D016896:Treatment Outcome
D007633:Keratins