title: Utility of proGRP as a tumor marker in the medullary thyroid carcinoma.
abstract: BACKGROUND
  Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor caused by a malignant transformation in the parafollicular C-cells of the thyroid, where calcitonin (CT) is released. Nowadays the main tumor markers (TM) used in the diagnosis and follow-up of MTC patients are CT and carcinoembryonic antigen (CEA). Nonetheless, progastrin releasing peptide (proGRP) has been recently proposed as a TM useful in the MTC. Our aims were to investigate the release of proGRP in thyroid tumors, its role in the assessment of advanced MTC and its utility in the differential diagnosis between MTC and non-MTC thyroid tumors.
  
  
  METHODS
  Serum samples from 22 patients with MTC and 16 with non-MTC were collected. Patients were classified into advanced cancer or no evidence of disease (NED). ProGRP was performed by Architect (Abbot Diagnostics), CT by Liaison (Diasorin) and CEA by Cobas E601(Roche Diagnostics).
  
  
  RESULTS
  ProGRP median concentration in advanced MTC was significantly higher (1398.4 pg/mL) when compared with non-MTC, either in advanced disease (24.9 pg/mL) or NED (14.6 pg/mL). In non-MTC patients, proGRP median concentration was below its cutoff level (50 pg/mL). Similar to CT, proGRP was able to detect 88.9% of MTC patients, but with a slightly lower specificity of 76.9%. Using proGRP together with CT the sensitivity increased to 100%.
  
  
  CONCLUSIONS
  The low prevalence of this malignancy strongly recommends further collaborative studies, mainly focused on monitoring proGRP during tyrosine kinase inhibitors treatment for early detection of resistance and assessing its usefulness to avoid the observed false positive fluctuations that occur with CT and CEA.
authors.forename: Marina
authors.initials: M
authors.lastname: Parra-Robert
authors.forename: Aida
authors.initials: A
authors.lastname: Orois
authors.forename: Josep Maria
authors.initials: JM
authors.lastname: Augé
authors.forename: Irene
authors.initials: I
authors.lastname: Halperin
authors.forename: Xavier
authors.initials: X
authors.lastname: Filella
authors.forename: Rafael
authors.initials: R
authors.lastname: Molina
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000097:blood / Q000556:secondary*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D002116:Calcitonin / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood; D002277:Carcinoma / Q000097:blood / Q000556:secondary*; D018278:Carcinoma, Neuroendocrine / Q000097:blood / Q000556:secondary*; D002291:Carcinoma, Papillary; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007118:Immunoassay; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood*; D011994:Recombinant Proteins / Q000097:blood; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000097:blood / Q000473:pathology* / Q000556:secondary; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D010446:Peptide Fragments; D011994:Recombinant Proteins; C087079:pro-gastrin-releasing peptide (31-98); D002116:Calcitonin