title: MEDULLARY THYROID CANCER THAT STAINS NEGATIVE FOR CA 19-9 HAS DECREASED METASTATIC POTENTIAL.
abstract: OBJECTIVE
  Presently, no clinical tools are available to diagnose the metastatic potential of medullary thyroid cancer (MTC) at disease presentation. Surveillance with calcitonin (Ct) and carcinoembryonic antigen (CEA) is currently recommended for the observation and diagnosis of metastatic disease after initial treatment of MTC. Recently, carbohydrate antigen (CA)19-9 staining has been associated with aggressive forms of MTC and metastatic spread. This pilot study explored whether positive CA19-9 staining of MTC tissue is associated with its metastatic potential.
  
  
  METHODS
  Sixteen cases of MTC were identified, and tissue specimens were immunostained for CA 19-9 and other MTC tumor markers. Clinical information about patients' MTC was collected through a retrospective chart review.
  
  
  RESULTS
  Overall, 63% of the specimens stained positive for CA19-9. The median size of positively staining specimens was 2.6 cm (interquartile range [IQR] 1.2-3.2) compared to 0.7 cm (0.5-1.2) in negatively staining MTC specimens (P = .04). All specimens from patients diagnosed with stage IV MTC stained positive for CA19-9, compared to only 40% of cases that were classified as stages I to III (P = .03). Furthermore, 100% of the primary specimens that were documented to have metastatic spread stained positive for CA19-9. The sensitivity for ruling out stage IV MTC based on negative staining for CA 19-9 was 100%.
  
  
  CONCLUSIONS
  Based on these results, we conclude that negative staining of MTC for CA19-9 may be associated with its decreased metastatic potential.
authors.forename: Sofiya
authors.initials: S
authors.lastname: Milman
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Arnold
authors.forename: Melissa
authors.initials: M
authors.lastname: Price
authors.forename: Abdissa
authors.initials: A
authors.lastname: Negassa
authors.forename: Martin I
authors.initials: MI
authors.lastname: Surks
authors.forename: Norman
authors.initials: N
authors.lastname: Fleischer
authors.forename: Kathleen D
authors.initials: KD
authors.lastname: Whitney
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018395:CA-19-9 Antigen / Q000032:analysis*; D018278:Carcinoma, Neuroendocrine / Q000737:chemistry* / Q000473:pathology; D002648:Child; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013964:Thyroid Neoplasms / Q000737:chemistry* / Q000473:pathology
chemical_list: D018395:CA-19-9 Antigen