Calcitonin precursor levels in human medullary thyroid carcinoma.
METHODS
The hormonal serum marker for the presence and course of patients with medullary thyroid cancer (MTC) is the mature calcitonin (CT) peptide. Other CALC-1 gene products such as the 116-amino acid polypeptide prohormone, procalcitonin, as well as its component calcitonin precursors (CTpr) may also be increased in their sera. We performed a study to evaluate the clinical utility of serum levels CTpr in these patients.


METHODS
Twenty-one patients with MTC (9 males, 12 females; 23-76 years of age) were evaluated. The diagnosis was confirmed by histologic examination, except for 2 (a proven RET mutation plus an abnormal pentagastrin-stimulated CT level). Nine patients had postoperative hypercalcitoninemia and 3 of these died. The specific assay for mature CT was a commercial immunoradiometric assay (hCT-IRMA); the immunoluminometric assay for CTpr (B.R.A.H.M.S Diagnostica, Berlin, Germany) detects intact procalcitonin and the free CT:CT carboxypeptide-1.


RESULTS
All patients had detectable serum CTpr. These levels considerably exceeded those of mature CT, averaging 7.6-fold greater. CTpr levels correlated positively with mature CT (r = 0.61; p < 0.001). After pentagastrin administration, there was a parallelism of response between the two assays. Whenever there were known metastases, CTpr increased markedly.


CONCLUSIONS
This study demonstrates the universal presence of CTpr in the blood of patients with MTC. The measurement of these peptides may offer a new dimension to the clinical evaluation of this malignancy.
Bihan
H
H
Avicenne Hospital, University of Paris XIII, Groupe d'Etudes des Tumeur à Calcitonine, Bobigny, France.
Becker
K L
KL
Snider
R H
RH
Nylen
E
E
Vittaz
L
L
Lauret
C
C
Modigliani
E
E
Moretti
J L
JL
Cohen
R
R
D014408:Biomarkers, Tumor / Q000097:blood; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D006801:Humans; D015513:Oncogene Proteins / Q000235:genetics; D011379:Prognosis; D011498:Protein Precursors / Q000097:blood*; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D012016:Reference Values; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000235:genetics
D014408:Biomarkers, Tumor; C000606589:CALCA protein, human; D015513:Oncogene Proteins; D011498:Protein Precursors; D002116:Calcitonin; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; D020794:Receptor Protein-Tyrosine Kinases; D015740:Calcitonin Gene-Related Peptide