CALCA and medullary thyroid gland carcinoma: When the diameter of the MTC lesions in the two groups was ≤1cm, the preoperative CEA level of the combined group was lower compared to the untreated group and the preoperative calcitonin level was not statistically significant; when the diameter of the MTC lesions in the two groups was < 1cm, the preoperative calcitonin level of the combined group was lower compared to the untreated group; the preoperative CEA level was not statistically significant.