title: Is her-2 status in the primary tumor correlated with matched lymph node metastases in patients with gastric cancer undergoing curative gastrectomy?
abstract: BACKGROUND
  HER2 expression in the primary tumor and its lymph node metastases vary in gastric cancer, reflecting intratumoral heterogeneity. This finding also suggests that proliferation of a different clone in metastatic nodes is possible. In the current study, we aimed to determine the cause of discordance in HER-2 expression in the primary tumor and lymph node metastases for patients with gastric cancer.
  
  
  METHODS
  Eighty-one patients with gastric cancer who had undergone radical gastrectomy and were found to have lymph node metastasis upon pathological examination were included. Histopathological samples were obtained from biopsies obtained during patient gastrectomies and lymph node dissection. HER2 status was evaluated by both immunohistochemistry (IHC) and silver in situ hybridization (SISH).
  
  
  RESULTS
  Sixty-four (79%) patients were SISH (-), while 17 (21%) were SISH (+) in the primary tumor. However, in metastatic lymph nodes, HER2 status was SISH positive in 5 (28.3%) of the 64 SISH (-) primary tumor specimens. One of the 17 SISH (+) primary tumors was SISH (-) in the metastatic lymph nodes. Thus, SISH results for HER2 in both primary tumors and lymph node metastases were comparable, showing a concordance of 92.5%. In total, six patients demonstrated discordance between the primary tumor and lymph node metastases. The prevalence of HER2 discordance was significantly higher for patients in the pN2 and N3 stages (p=0.007). Although discordant patients had worse survival rates than concordant patients, the differences were not significant (p>0.05).
  
  
  CONCLUSIONS
  Our study indicates that the frequency of concordance in HER2 status, as determined by IHC or SISH, is high in primary tumors and their corresponding lymph node metastases for patients with gastric cancer. If there is a discrepancy in HER2 status, its evaluation by both IHC and SISH may be useful for detecting patients who would benefit from trastuzumab, and it would therefore help guide decision-making processes in administering treatment.
authors.affiliation: Sisli Education and Research Hospital, Department of Medical Oncology, Istanbul, Turkey E-mail : fsbiricik@yahoo.com.
authors.forename: Fatih
authors.initials: F
authors.lastname: Selcukbiricik
authors.forename: Sibel
authors.initials: S
authors.lastname: Erdamar
authors.forename: Evin
authors.initials: E
authors.lastname: Buyukunal
authors.forename: Suheyla
authors.initials: S
authors.lastname: Serrdengecti
authors.forename: Fuat
authors.initials: F
authors.lastname: Demirelli
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D005260:Female; D005500:Follow-Up Studies; D005743:Gastrectomy / Q000401:mortality*; D006801:Humans; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D007414:Intestinal Neoplasms / Q000378:metabolism / Q000401:mortality / Q000556:secondary* / Q000601:surgery; D008198:Lymph Nodes / Q000473:pathology / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000378:metabolism / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D009367:Neoplasm Staging; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000378:metabolism / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human