Detection of disseminated tumor cells in the lymph nodes of colorectal cancer patients using a real-time polymerase chain reaction assay.
BACKGROUND
Postoperative treatment for colorectal cancer depends on tumor stage as defined by the International Union Against Cancer (UICC). Adjuvant chemotherapy is not recommended in patients without lymph node involvement (UICC stages I and II). As many as 20-30% of these patients, however, will develop recurrence.


OBJECTIVE
We conducted this study to determine the presence of disseminated tumor cells in the lymph nodes by quantitative real-time polymerase chain reaction (QRT-PCR) for cytokeratin 20 (CK20) in an attempt to provide supplementary information compared to histopathological findings.


METHODS
Using a standard QRT-PCR assay, we examined primary tumors and 391 lymph nodes from 31 patients with completely resected colorectal cancer.


RESULTS
Of the 31 primary tumors, 29 were positive for CK20 by QRT-PCR.


CONCLUSIONS
An examination of the lymph nodes from the 29 patients with CK20-positive primary tumors revealed that 35 (92.1% sensitivity) of the 38 histopathologically positive lymph nodes and 54 (16.7%) of the 324 histopathologically negative lymph nodes were positive by molecular analysis. CK20 expression was detected in 10 (100%) of 10 patients with a histopathologically positive lymph node status (pN1). In 9 (47.4%) of 19 patients with negative histopathological results (pN0), we detected a CK20 mRNA signal in at least one lymph node. Whereas eight patients with histopathologically negative lymph nodes could be upstaged on the basis of the molecular findings, no patient would be downstaged.


CONCLUSIONS
Our results suggest that QRT-PCR for CK20 is a useful tool for the quantitative detection of micrometastases in the regional lymph nodes. We introduce a standardized procedure that integrates a molecular diagnostic technique in the clinical staging.
Lotspeich
Erkki
E
Department of Surgery, German Armed Forces Hospital, Oberer Eselsberg 40, 89081, Ulm, Germany. erkki.lotspeich@gmx.de
Schoene
Markus
M
Gerngross
Heinz
H
Schmidt
Roland
R
Steinmann
Reinhard
R
Ramadani
Marco
M
Gansauge
Susanne
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D053554:Keratin-20 / Q000235:genetics*; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D014408:Biomarkers, Tumor; D053554:Keratin-20; D012333:RNA, Messenger