CALCA and neoplasm: Single factor Kaplan-Meier (K-M) analysis showed that: 1 Preoperative ultrasonic characteristics including tumor size > 40.0 mm, capsular invasion, and metastatic cervical lymph nodes, as well as preoperative calcitonin level > 565.8 pg/ml, and postoperative calcitonin (within one week) level > 45.0 pg/ml were positively correlated with the risk of postoperative recurrence of MTC (P < 0.05); 2 There was no evidence to show that sex and age had a statistically significant effect on postoperative recurrence of MTC (P > 0.05).