The tumor recurrence/persistence group showed significantly higher levels of serum calcitonin (mean 563.2 ± 1362.4 pg/mL, range 6.1–5545.0 pg/mL) than the non-recurrence group (mean 3.2 ± 2.2 pg/mL, range 1–9.3 pg/mL). The gene discussed is CALCA; the disease is neoplasm.