Detection of occult micrometastases in non-small cell lung carcinoma by reverse transcriptase-polymerase chain reaction.
BACKGROUND
The 5-year survival rate following surgical resection of Stage I or Stage II non-small cell lung carcinoma (NSCLC) is 30% to 50%, probably because of undetected occult micrometastases (OMs) at the time of surgery. Other investigators have detected OMs in bone marrow and histologically negative lymph nodes from patients with NSCLC using immunohistochemical staining to cytokeratins and cell surface glycoproteins.


OBJECTIVE
To develop and evaluate an assay based on the reverse transcriptase-polymerase chain reaction (RT-PCR) for the detection of OMs in NSCLC.


METHODS
Twenty-eight patients with benign or malignant thoracic pathology. Samples of primary tumors and lymph nodes were collected at the time of surgical resection or mediastinoscopic lymph-node biopsy.


RESULTS
Using RT-PCR to detect messenger RNA (mRNA) transcripts for MUC1 (a cell surface glycoprotein present in lung tissue but absent from normal lymph nodes), OMs were identified in 33 of 88 lymph nodes determined to be free of tumor by hematoxylin and eosin staining. Eleven of 11 control mediastinal lymph nodes from patients without malignancy failed to express detectable MUC1 transcripts. Dilutional experiments demonstrate that the assay can detect one MUC1-positive NSCLC cell in 1x10(7) MUC1-negative cells. A comparison of our RT-PCR assay to immunohistochemistry specific for the MUC1 glycoprotein suggests that RT-PCR may be more sensitive than immunohistochemistry for the detection of NSCLC OMs.


CONCLUSIONS
This study demonstrates that RT-PCR for MUC1 mRNA can detect the presence of MUC1 mRNA in histologically negative lymph nodes from patients with NSCLC. The prognostic significance of these findings is currently unknown.
Salerno
C T
CT
Department of Surgery, University of Minnesota, Minneapolis V.A. Medical Center, USA.
Frizelle
S
S
Niehans
G A
GA
Ho
S B
SB
Jakkula
M
M
Kratzke
R A
RA
Maddaus
M A
MA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000737:chemistry / Q000175:diagnosis* / Q000556:secondary*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000737:chemistry / Q000473:pathology*; D008198:Lymph Nodes / Q000737:chemistry; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000032:analysis / Q000235:genetics; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012194:RNA-Directed DNA Polymerase; D012680:Sensitivity and Specificity
D018396:Mucin-1; D012333:RNA, Messenger; D012194:RNA-Directed DNA Polymerase