Half-life of alpha-fetoprotein in neonatal sacrococcygeal teratoma.

BACKGROUND: Alpha-fetoprotein (AFP) is useful as a tumor marker for sacrococcygeal teratoma (SCT). We investigated the half-life of AFP in SCT.

METHODS: Neonates who underwent surgical treatment for SCT between 1997 and 2016 were included in the study, whereas patients who died before or after surgery or had malignant germ cell tumors were excluded.

RESULTS: Fifty-five non-recurrent SCT patients (M:F = 18:37) were enrolled. They underwent surgery on average 7.4 ± 4.1 days after birth. Serum AFP was measured an average 4.25 ± 2.07 times per patient. We obtained 165 half-lives following the formula (M = Mo * (1/2) Δt/T ). A positive correlation was observed between half-life and patient age using the formula T1/2  = 0.0597 × days +6.1643 (p < 0.001). It was different from recurrent SCT (T1/2  = 0.1196 × days -0.0633) (p < 0.05). Half-life was different between mature SCT (T1/2  = 0.0671 × days +4.3912) and immature SCT (T1/2  = 0.0433 × days +8.9339) (p < 0.05).

CONCLUSION: The half-life of AFP in neonatal patients with SCT was prolonged in proportion to the age, and it was getting longer in recurrent tumor than non-recurrent tumor. The half-life of AFP was longer in immature teratoma than in mature teratoma.

LEVEL OF EVIDENCE: IV.