Comparison of PCR-based detection of chromogranin A mRNA with traditional histological lymph node staging of small intestinal neuroendocrine neoplasia.
BACKGROUND
Accurate neuroendocrine neoplasia (NEN) staging is vital for determining prognosis and therapeutic strategy. The great majority of NENs express chromogranin A (CgA) which can be detected at a protein or transcript level. The current standards for lymph node metastasis detection are histological examination after Hematoxylin and Eosin (H&E) and CgA immunohistochemical (IHC) staining. We hypothesized that detection of CgA mRNA transcripts would be a more sensitive method of detecting these metastases.


RESULTS
We compared these traditional methods with PCR for CgA mRNA extracted from formalin fixed paraffin embedded slides of lymph nodes (n = 196) from small intestinal NENs, other gastrointestinal cancers and benign gastrointestinal disease. CgA PCR detected significantly more NEN lymph nodes (75%) than H&E (53%) or CgA IHC (57%) (p = 0.02). PCR detected CgA mRNA in 50% (14 of the 28) of SI-NEN lymph nodes previously considered negative. The false positive rate for detection of CgA mRNA was 19% in non-neuroendocrine cancers, and appeared to be due to occult neuroendocrine differentiation or contamination by normal epithelium during histological processing.


CONCLUSIONS
Molecular pathological analysis demonstrates the limitations of observer-dependent histopathology. CgA PCR analysis detected the presence of CgA transcripts in lymph nodes without histological evidence of tumor metastasis. Molecular node positivity (stage molN1) of SI-NEN lymph nodes could confer greater staging accuracy and facilitate early and accurate therapeutic intervention. This technique warrants investigation using clinically annotated tumor samples with follow-up data.
Gastrointestinal Pathobiology Research Group, Yale University School of Medicine, New Haven, CT 208602, USA.
Ben
B
Lawrence
Barton
B
Kenney
Bernhard
B
Svejda
Simon
S
Schimmack
Daniele
D
Alaimo
Andrea
A
Barbieri
Jaroslaw
J
Jedrych
Mark
M
Kidd
Irvin
I
Modlin
D014408:Biomarkers, Tumor / Q000235:genetics*; D018278:Carcinoma, Neuroendocrine / Q000175:diagnosis* / Q000235:genetics / Q000556:secondary; D053379:Chromogranin A / Q000032:analysis / Q000235:genetics*; D005240:Feasibility Studies; D006801:Humans; D007150:Immunohistochemistry; D007414:Intestinal Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D007421:Intestine, Small / Q000473:pathology; D008198:Lymph Nodes / Q000737:chemistry* / Q000473:pathology; D008207:Lymphatic Metastasis; D061206:Neoplasm Micrometastasis; D009367:Neoplasm Staging; D015588:Observer Variation; D016612:Paraffin Embedding; D011237:Predictive Value of Tests; D012333:RNA, Messenger / Q000032:analysis*; D060888:Real-Time Polymerase Chain Reaction; D015203:Reproducibility of Results; D016707:Tissue Fixation
D014408:Biomarkers, Tumor; C506150:CHGA protein, human; D053379:Chromogranin A; D012333:RNA, Messenger